Common section

Chapter 1

Deep structure

Braudel wrote of the first part of his classic study of the Mediterranean that it dealt with 'all the permanent, slow-moving, or recurrent features of Mediterranean life. In the pursuit of a history that changes little or not at all with the passing of time, I have not hesitated to step outside the chronological limits of a study devoted in theory to the latter half of the sixteenth century.'1 This is what I aim to do in this chapter. And like Braudel I am not limiting my study to any discrete time period. I then can draw data from about five millennia, always however being aware that this must be data to do with invariant matters. I will discuss the name of the ocean, its geographical boundaries, its topography, winds and currents, and then introduce people. This is when the whole study of deep structure will become problematic and complicated, as we will see.

Frank Broeze suggested that the term 'Indian Ocean' is inappropriate. He wrote of 'a string of closely related regional systems stretching from East Asia around the continent and across the Indian Ocean to East Africa (to which sea space a new generic name, such as "the Asian Seas", might well be given)'.2 Despite my customary privileging of India, I also have some hesitancies about the term 'the Indian Ocean'. The terminology implies that India is the centre, the fulcrum, but this needs to be demonstrated, not just assumed. I recently argued that a better name for the part of the Indian Ocean known as the Arabian Sea was the Afrasian Sea. 'The Arabian Sea' seems to give Arabs a role much more prominent than is appropriate. Some years ago people began to write about Eurasia, the idea being to stress connections rather than the artificial separation between a reified (and implicitly successful) Europe and a timeless (implicitly backward, even redundant) Asia. We were reminded of millennia of contact, especially between the eastern Mediterranean and the Arabian Sea. Now some have urged us to go further still. In what seems to be the ultimate uniformitarianism, the desire to show 'one world' before capitalism, to stress links between areas long before the European voyages, the term Afrasia has been suggested. This would make up a vast area, with western Europe to be seen as a tiny appendage on the western edge. But this also is controversial, for it is stretching things to see most of sub-Saharan Africa sharing in the history of Eurasia before the European voyages. This however does not apply to the

Swahili coast. I suggested that the appropriate term for what used to be called the Arabian Sea could be the Afrasian Sea. This is an encompassing term and does include East Africa. Chandra de Silva recently wrote that it was incorrect to call this coast part of the Indian Ocean, and I agree with him, but to separate it out and call it the African Sea, as he suggests, seems unnecessarily divisive: the great advantage of the Afrasian Sea notion is its inclusiveness, and its failure to imply the dominance of any one area around the shore.3

Mutatis mutandis, I could now argue that this term would be even more appropriate for the whole area of what is conventionally called the Indian Ocean, for it would avoid assuming Indian centrality as implied in the Indian Ocean term, or Arab dominance as in the Arabian Sea, and instead would be all inclusive, taking in not only the Asian shores, which clearly are most important if only because of length, but including also the often ignored area of the East African coast. Yet this book is called The Indian Ocean so, a little reluctantly, I must continue to use this term. I will also use the familiar term of the Arabian Sea, while, to demonstrate impartiality, the Persian/Arabian Gulf will be simply the Gulf. My aim so far has merely been to alert the reader to the assumptions, arguably invalid, in the use of this term. It really all depends on where one is standing when one looks at and names an ocean. After all, Arabs refer to the Mediterranean as the Syrian Sea.

In any case, to assume that the Indian Ocean unduly emphasises India is to ignore the way a major group who were not Indian referred to the area. Arabs were happy to call the ocean al-bahr al Hindi, and indeed our term the Indian Ocean is an exact translation of this Arabic phrase. Hind derived from the Sanskrit, sindhu, to Persian and Arabic hind, and then via Greek and Latin to modern European languages as some variant of India. It is true that sometimes the Arabs were referring only to the Arabian Sea, but at times they also seem to have used the term to refer to an area that we today call the Indian Ocean.

The Indian Ocean covers some 27 per cent of the maritime space of the world. It is the third largest ocean in the world, and covers 14 per cent of the total globe. Before I try to delineate its borders, we can first consider the whole matter of borders as such. One of the great advantages of writing maritime history, or for that matter the currently fashionable world history, is that by definition one escapes the land/political borders which have shackled traditional history for so long. States fade into the background in this sort of history, and we can look rather at 'worlds' and 'zones', along the lines of the MCC discussion in the introduction (see page 7). This said, I still have to depict the geographic (not human) limits of the Indian Ocean.

It is fairly straightforward. The longitudes are roughly 20° E to 110° E. Southern Africa, more precisely Cape Agulhas, is one limit, and we then go around the coast, including the Red Sea and the Gulf, past South Asia and through the Bay of Bengal and so to what geographically is the obvious limit, that is the Malay peninsula and the Sunda Islands. Past this the monsoons change. Possibly the Sunda Deep of the Java Trench off the southern coast of Java, which is 24,442 feet (7,450 metres) deep, forms a bathymetric boundary which separates the southeast Asian maritime region from the Indian Ocean. From here we go south to Cape Leeuwin in southwest Australia.

So far we have followed the borders as recognised by the United Nations Oceans Atlas, and the International Hydrographic Organisation (IHO), but both these authorities then go past Western Australia to around Melbourne, the west coast of Tasmania, and then down to Antarctica. This opinion is not to be taken lightly, especially as it is congruent with those of Alan Villiers, who was a real sailor.4 Nevertheless, I would be inclined to stop at Cape Leeuwin, and go no further east. Certainly I agree with the International Hydrographic Organisation on the southern boundaries. In early 2000 the IHO delimited a fifth world ocean, the southern parts of the Atlantic, Indian and Pacific. This extends from the coast of Antarctica to latitude 60° S.5 We still have a lot of the Great Southern Ocean included in the Indian Ocean, including the peri-Antarctic islands on either side of 45° S, namely the Prince Edward Islands, Iles Crozet, Iles Kerguelen, Ile Amsterdam, Ile Saint-Paul, McDonald Islands, and Heard Island. From the late eighteenth century these islands provided places for sealers to winter, and today most of them have permanent populations of scientists, but they will play a small part in our history of the Indian Ocean.6 They will be of interest only when we have ships using the roaring 40s and the fearsome 50s as they go from one end of our ocean, south Africa, to another, western Australia.7 For most of history ships never went below the tropic of Capricorn.

One way to visualise what I think of as the Indian Ocean proper is to see it as a vast equilateral triangle. The base is the tropic of Capricorn, that is 23° 27' S. The two sides go north, the western one then including the Swahili and south Arabian coasts, up to north India, and then down from the apex through Burma, Sumatra and to northwest Australia. The only real problem with this is that it excludes the Gulf and Red Sea, and these were intricately connected with the Indian Ocean; apart from this it works quite well to depict the area of concern in this book. An alternative, perhaps even one to be preferred, is to see it as a vast letter M, with the Red Sea and Gulf on one side, and the Bay of Bengal on the other, divided by India.

The ocean proper, the vast wide expanse of water that we quoted Conrad on in the introduction (see pages 1–2), was well described by a Persian traveller in the eighteenth century:

It is not possible to measure the full extent of that sea except with the eye of fantasy. No one will ever delve to the bottom of that sea except by plunging into the waves of his wildest dreams. We were surrounded by a limitless desert of water. The days were white and the nights were black. You could not spy a single speck afloat on those fields of water, only the dark blue of the heavens reflected on the blue black of the sea.8

Opposed to this are the various bays and smaller seas and gulfs. Joseph Conrad saw the bays, in this case the Gulf of Thailand, as being rather different from the real ocean. One of his characters said that

from Bankok [sic] to the Indian Ocean was a pretty long step.... Extreme patience and extreme care would see me through the region of broken land, of faint airs, and of dead water to where I would feel at last my command on the great swell and list over to the great breath of regular winds, that would give her the feeling of a large, more intense life.9

If then there is a wide, expansive Indian Ocean, around its edges and margins are a host of seas. Among them are the Mozambique Channel, Red Sea, Gulf of Aden, Arabian Sea, Persian Gulf, Gulf of Oman, Bay of Bengal, Andaman Sea, Strait of Melaka, and the Laccadive Sea. Yet the same Sulaiman who wrote about the vast, open ocean also commented sourly on too much schematisation; he travelled where I have not been, and so must be listened to:

There is not really a clear separation between the seas we crossed [from the Gulf to Siam]. An ordinary traveller would not be able to perceive where one sea ended and the next began. . . . The scholars of travel and geography, confronted with many different place names... have wandered into the discords of choppy seas, doldrums and foul winds and they divide the great expanse of water which lies along this path into seven distinct parts.10

The topography obviously varies from place to place, being for example quite different in the bays as compared with coasts exposed to the wide ocean. Some shores are uninhabited desert, others cut off from the interior by impenetrable mountains, but most of the shores of the Indian Ocean are not quite as inhospitable as these examples. In India a fertile coastal fringe, especially in the south, the area of Kerala, is backed by the high mountain range called the western Ghats, but these are nowhere completely impassable. So also on the Swahili coast, where again behind a productive coastal zone is the nyika, a mostly barren area difficult, but not impossible, to travel through on the way to more fertile land further inland. On the northern shores of the ocean the coastal fringe is mostly much less productive, and leads to inland areas which often are hostile deserts. Yet topography has favoured this area even so, for the Red Sea goes into the Gulf of Aden, and this gives places around there, especially the Hadhramaut area east of Aden, a possible role in servicing ships going to East Africa or western India.

We will discuss islands presently, but most of those in the Indian Ocean proper are relatively isolated and scattered. Such is not the case in Indonesia, and this then provides another reason to place this area outside the Indian Ocean proper. Geography makes the sea in the island-studded Malay world much more central; if one likes, this is a much more maritime area, both topographically, and (as we will see soon) humanly. The region has an extremely high ratio of coastline to land area; indeed the highest in the world if one takes into account population.11 The Malay world can be seen as a Mediterranean area, just like the Gulf of Mexico/Caribbean area. All three are enclosed, but with access to oceans, that is to the Indian Ocean and Pacific in the first, to the Atlantic in the last two. And when we add in rivers this applies even more strongly to make this a much more aquatic area, strongly contrasting with the situation in the Indian Ocean. The only comparable area in the true Indian Ocean may be the area that the Portuguese called the Sea of Ceylon, that is the narrow strait of the Gulf of Mannar between Sri Lanka and southeast India, where again geography dictates that the sea is much more central simply because it is close on both sides of this passage.

Choke points are another topographical matter that influence the nature of the Indian Ocean. The Straits of Melaka, at their narrowest, where they join the Singapore Strait north of the Karimum Islands, are only 8 nautical miles wide. and today are used by 50,000 ships a year, including small country craft. The actual width of the channel that ships can use in this area is only 2½ miles off Melaka and a mere 1 mile off Singapore. The Persian/Arabian Gulf at its narrowest section, in the Straits of Hurmuz, is only 48 km (21 nautical miles) wide, and passage is made more difficult by many islands and reefs. The Suez Canal is an obvious choke point, as also is the Strait of Tiran, which is only about 5 kms wide at its narrowest point. At the entrance to the Red Sea, the Bab al Mandeb at its narrowest is only 12 kms wide. It is at these choke points that port cities are usually found, as we will see.

Topography provides other important bounds and constraints. Some areas were very difficult to navigate. The Gulf is one such, but the Red Sea provides the best example. Past Jiddah was especially bad, so that only small specialised ships could make the passage from there to Suez. An Arabic account from the ninth century makes clear the dangers. Ships from the Gulf port of Siraf

put into Judda, where they remain; for their Cargo is thence transported to Kahira [Cairo] by Ships of Kolzum, who are acquainted with the Navigation of the Red Sea, which those of Siraf dare not attempt, because of the extreme Danger, and because this Sea is full of Rocks at the Water's Edge; because also upon the whole Coast there are no Kings, or scarce any inhabited Place; and, in fine, because Ships are every Night obliged to put into some Place of Safety, for Fear of striking upon the Rocks; they sail in the Day time only, and all the Night ride fast at Anchor. This Sea, moreover, is subject to very thick Fogs, and to violent Gales of Wind, and so has nothing to recommend it, either within or without.12

A pilgrim in 1183 wrote of the entry to the important port of Jiddah:

The entry into it is difficult to achieve because of the many reefs and the windings. We observed the art of these captains and the mariners in the handling of their ships through the reefs. It was truly marvellous. They would enter the narrow channels and manage their way through them as a cavalier manages a horse that is light on the bridle and tractable. They came through in a wonderful manner that cannot be described....

He had been eight days at sea, and it had been a hazardous time:

There had been the sudden crises of the sea, the perversity of the wind, the many reefs encountered, and the emergencies that arose from the imperfections of the sailing gear which time and again became entangled and broke when sails were raised or lowered or an anchor raised. At times the bottom of the jilabah would run against a reef when passing through them, and we would listen to a rumbling that called us to abandon hope. Many times we died and lived again.13

Daniel's account in 1700 similarly makes clear the hazards, in this case on a voyage from Suez to Yanbo, the port of Medina. His ship anchored each night in order to avoid reefs, rocks and shoals, and this short voyage took from 12 July to 10 August. They only reached Jiddah on 29 August.14 One of our most graphic accounts comes from Tomé Pires in the early sixteenth century. In the Red Sea

there are many rocky banks and they are difficult to navigate. Men do not navigate except by day; they can always anchor. The best sailing is from the entrance to the strait as far as Kamaran. It is worse from Kamaran to Jiddah and much worse from Jiddah to Tor. From Tor to Suez is a route for small boats even by day, because it is all dirty ('cujo') and bad.15

In our own time it has got no better. Jacques Cousteau sailed there many times, but even in the early 1950s much of it was uncharted and very dangerous. This applied especially to the Far-Sans reef complex, 350 miles long and 30 miles wide, along the Yemen and Hijaz coasts. It is a 'demented masterpiece of outcrops, shoals, foaming reefs, and other lurking ship-breakers.' Things are made worse by another deep structure element, the winds, which for most of the year are north and north-westerly, so that sailing south is extremely hot.16

Scorching winds were an environmental hazard which many travellers commented on. Isabel Burton was in Aden in January 1876 and found it very hot: 'I think it is to Aden that is attached the legend of the sailors who died and went to a certain fiery place, and appeared, and on being asked why they came, they replied that they had caught cold, and had leave to come to fetch their blankets.'17 Similarly Marco Polo in Hurmuz: 'The fact, you see, that in summer a wind often blows across the sands which encompass the plain, so intolerably hot that it would kill everybody, were it not that when they perceive that wind coming they plunge into water up to the neck, and so abide until the wind have ceased.'18

We have noted the dense network of islands characteristic of the Malay world. The more isolated islands in the ocean play a rather different role. Geologically they are various. Some are granite fragments of larger land masses, such as Madagascar, Sri Lanka, Socotra and part of the Seychelles. Other are volcanic from submarine eruptions: Mauritius, Reunion, Comoros, Kerguelen, while others are formed by coral buildup, such as the Cocos Islands. Many were unpopulated until recent times, yet in the last few centuries several of them, taking account of the deep structure matter of their location, have acted as hinges, connecting very distant parts of the ocean. There are of course variations to do with size and distance from the continent: for example, Sri Lanka has been profoundly influenced by its larger neighbour to the north. Some smaller islands contiguous to the continent are hardly to be considered as islands at all. Kilwa, Mombasa, the islands off the Burma coast, are really just partially detached parts of the mainland. Others are so large as to share mainland characteristics, where the influence of the sea is not paramount: Madagascar, Sumatra, obviously Australia.

Even these deep structural topological characteristics of our ocean can change over time. We will consider changes in climate presently, but some coastal areas have been profoundly affected by other factors, most obviously the silting up of rivers. The Gulf of Cambay has contracted quite substantially. Once it extended up to where Ahmadabad is located. Vallabhi, now 40 kms inland, was once a riverine port. The ground level at the spot where the Tigris and Euphrates meet has risen 20 feet over the last few millennia.

The next deep structure element in the Indian Ocean which constrained human movement was the monsoon winds. Felipe Fernández-Armesto claims that what really matters in maritime history is wind systems, and especially the difference between monsoonal systems, and those with year-long prevailing winds. The monsoons follow a quite regular pattern, in the Arabian Sea essentially southwest from May to September, and northeast from November to March. This relatively predictable pattern contrasts strongly with trade wind regions like the Atlantic, where there is a regular pattern of prevailing winds year-round: essentially northeast in the northern hemisphere, southeast in the southern, though both veer more easterly nearer the equator. They are separated, around the equator, by doldrums. North and south of the trades are westerlies, especially strong in the southern hemisphere. While both oceans have predictable winds, more or less, it is clearly much easier to do a round trip in the Indian Ocean than it is in the Atlantic. 'The predictability of a homeward wind made the Indian Ocean the most benign environment in the world for long-range voyaging.'19

In simple terms, the monsoons are generated by the rotation of the earth, and by climate. Heat during the summer warms the continental land mass in the north of the ocean. Hot air rises and creates a low pressure zone at the earth's surface. Moisture-laden air from the sea then moves in to this low pressure area, rises in the upward air current, cools, and so produces clouds and rain. In winter the reverse occurs; as the sea cools more slowly than the land, winds flow out from the land. This pattern is most clearly seen in the Arabian Sea, thanks to the high plateau of Tibet to the north, and warm tropical seas to the south. Another arm of the southwest monsoon avoids southern India and flows directly over the Bay of Bengal to Bengal and Bangladesh: these areas often get the monsoon before Mumbai. It is also in this area that the monsoons sometimes progress into the notoriously destructive and all too common tropical cyclones, with winds over 120 kph, and sometimes reaching 200 kph with gusts even up to 400 kph.

It was these winds which very largely determined when people could sail where. The monsoon winds were absolutely vital, even if Felipe Fernández-Armesto was putting it a bit strongly when he wrote that

Throughout the age of sail – that is, for almost the whole of history – wind determined what man could do at sea: by comparison, culture, ideas, individual genius or charisma, economic forces and all the other motors of history meant little. In most of our traditional explanations of what has happened in history there is too much hot air and not enough wind.20

There are some regional specificities and details to consider, these acting to complicate the simple pattern outlined above, and also to put a premium on experience and knowledge. The pattern of winds in the Arabian Sea is familiar enough. Many authorities stress the divide of the Swahili coast at Cape Delgado, which is just south of the mouth of the Ruvuma River, which river forms the boundary today between Tanzania and Mozambique. As a rule of thumb, down to Cape Delgado is one monsoon from Arabia and India, but south of there is two. Here then we see a deep structure element, the monsoons, privileging the northern Swahili coast, for it was more accessible to centres in India and Arabia than was the south.

The northeast monsoon starts in November and one can leave the Arabian coast at this time and reach at least Mogadishu. However, the eastern Arabian sea has violent tropical storms in October and November, so for a voyage from India to the coast it was best to leave in December, by which time the northeast monsoon was well established as far south as Zanzibar: a rapid passage of twenty to twenty-five days could be expected. By March the northeast monsoon was beginning to break up in the south, and by April the prevailing wind was from the southwest. This was the season for sailing from the coast to the north and east. At its height, in June and July, the weather was too stormy, so ships departed either as this monsoon built up in May, or at its tail end in August. An important general point here is that both monsoons prevailed longer the further north on the coast one was. In the far south we are really outside the monsoon system. In particular, the southwest monsoon is not nearly as strong and predictable as it is further north in the monsoon zone. Up to Mozambique Island there was really no monsoon, and indeed some would claim that the notion of a monsoon system really only applies in the northern hemisphere, or at most to about 10° S.

Moving around to the Red Sea area and southern Arabia, there were other particular things to take account of. An English traveller in 1780 wrote of the pattern in and around the Red Sea:

As different winds prevail on the different sides of the Tropic in the Red Sea, ships may come to Gedda [Jiddah] from opposite points at the same season of the year; those which come from Suez at the above mentioned time [that is, November to January], benefit by the N.W. wind, while those that come from India and Arabia Felix are assisted by the regular S.W. monsoon. The pilgrims... embark at Gedda time enough to avail themselves of the Khumseen [according to Capper this is Arabic for 50, which is the length of time this wind blows] wind, which blows southerly from the end of March to the middle of May, and conveys them in less than a month back again to Suez; the India vessels must also quit Gedda so as to be out of the straits of Babelmandel before the end of August.21

Even today within the Red Sea the monsoons act as a governing factor for traditional navigators, as a modern account of the sea's routes, winds and sailing times makes clear.22

This situation of course pertained even more strongly concerning the traffic between the Red Sea and western India. In the great fifteenth-century trade between Calicut and the Red Sea, ships left Calicut in January, and vessels from the Red Sea arrived there between August and November. The Portuguese described the military significance of this on the Malabar coast. The west coast of India was unnavigable for sailing ships between roughly June and September. In the 1530s the Portuguese were concerned at the way ships from the hostile port of Calicut could sail just before or just after this, before their blockading fleets could arrive. The solution seemed to be to build a fort very near to Calicut. Then they could patrol right up to the end of May, just before navigation became impossible, and resume the blockade early in September as soon as the slackening of the southwest monsoon made navigation possible again.23

As for Gujarat, Terry wrote that the great ship going from Surat to Mocha

beginnes her voyage about the twentieth of March, and finisheth it towards the end of September following. The voyage is but short and might easily bee made in two months; but in the long season of raine, and a little before and after it, the winds are commonly so violent that there is no coming but with great hazard, into the Indian Seas.24

The matter was most pithily expressed by an Arab author, who wrote that 'He who leaves India on the 100th day [2 March] is a sound man, he who leaves on the 110th will be all right. However, he who leaves on the 120th is stretching the bounds of possibility and he who leaves on the 130th is inexperienced and an ignorant gambler.'25

Moving south to the end of the ocean, the west coast of Malaysia is a lee shore during the southwest monsoon, and at this time it is, just as on the west coast of India, very difficult to sail or land. This monsoon pattern also dictated that a passage from the far west of the ocean, say the Red Sea, to the far east, to Melaka, could not be accomplished in one hit; rather a stop over was necessary, probably in southern India, until the correct monsoon came to continue one's voyage.

Those who ignored the monsoons, or were ignorant of them, came to grief. In 1541 a Portuguese marauding fleet in the Red Sea set sail to return to India in early July. The headstrong captain refused to listen to the advice of his Muslim pilots, who, basing their views on centuries of experience, told him that by leaving at this time he would have no trouble getting to the entrance to the Red Sea, but that once in the Arabian Sea weather of such vileness could be expected that no ship could navigate. And this advice, of course, turned out to be correct.26 In 1980 Tim Severin, sailing on his Sindbad voyage from the Gulf to China, was becalmed east of Sri Lanka on the replica dhow Sohar for thirty-five days in March and April; earlier voyagers could have told him that this would happen.27

All this said, it is not quite as clockwork like as some accounts claim. For example, Severin picked up the southwest wind that he wanted in early April, which is much earlier than the books allow for. Thor Heyerdahl, in another replica boat, this one made of reeds, passed the Straits of Hurmuz and knew he was now in the monsoon area, which 'blows regularly across the Indian Ocean as if set in motion by clockwork, turning like a pendulum to move in opposite directions every half year.' However, what happened next showed how variable they can be. In January they picked up a faint south-southwest wind, 'and there was no sign of the strong northeast winter monsoon we could have expected in the middle of January'. The next day, before sunrise, the wind changed from south-southeast to north-northwest – in other words still coming from the wrong direction.28

For monsoon Asia the arrival of the rain-bearing southwest wind is vital, not only for maritime affairs but also for the much more basic matter of growing crops. In India, for example, there are monsoon ragas, they are a theme in miniature painting, and in some of the works of the poet Kalidasa. There are also methods to cope with any variability, again then showing that they are not totally predictable. Andrew Frater wrote engagingly about the problem if they are late, or fail altogether:

The previous year [1986] in Bangalore, for example, the city fathers paid a yogi to pray for rain. Seated on a tigerskin rug beside the Bangalore Water Supply and Sewerage Board guesthouse, the yogi chanted for 2 hours and 4 minutes while his supporters chewed leaves and swallowed burning camphor. Afterwards he was able to inform senior Water Board officials – prostrated before him with offerings of coconuts – that the rain god Varuna, though invisible to the naked eye, now approached them 'like waves of clouds.' The rain fell, all right, and torrentially, but only over neighbouring Cochin.29

The implications of the monsoons are endless, and will underlie most of our discussion of movement by sea before the age of steam. Pirates moved according to the season, leaving the west coast of India for the Bay of Bengal around May each year. They also affect fisheries. Along the southeast Arabian and Somali coasts when the strong winds of the southwest monsoon blow coastal water away from the shore, one gets an upwelling of nutrient rich cold water This may have ten or even twenty times the nutrients of normal surface water. One gets rich blooms of plankton, ideal for fish. However, if this goes on too long the plankton becomes too thick. Lack of oxygen kills the fish. In 1957 such a bloom was estimated to have killed the equivalent of the world's entire fish catch for a year.30

The monsoons are essentially tropical winds. The further south one goes the weaker they are. In the southeast African case, up to Mozambique Island there was really no monsoon. Square rigged ships had to wait for the occasional cold front from Antarctica, take it until it petered out, and then wait for the next one. And there is the added complication of doldrums around the equator, nowhere near as bad as those in the Atlantic that Coleridge wrote about so powerfully, but still at times a hazard or an inconvenience.

South of the monsoon region lies a belt of southeast trade winds, around 15 to 30° S. These are more or less year-round. Alan Villiers took these once. In the 1930s he was crew on a big four-master barque with thirty sails and 35,000 square feet of canvas. These huge ships were very definitely not the more famous clipper ships, which he dismissed as 'lightly loaded kite-filled clippers'. This ship, and the other Cape Horn ships, he considered as 'Among man's working creations for the carriage of his goods, they alone were supremely beautiful.'31 The cargo was 5,000 tons of Victorian grain. The ship picked up an easterly as they left Melbourne, so the captain decided to go via the Cape of Good Hope rather than the more usual Cape Horn. Past Cape Leeuwin they got the southeast trades in latitudes 25–28° S. These would carry them to the south of Madagascar, where they would pick up the Agulhas current which would take them southeast to the Cape. Once around this they could pick up the southeast trades in the Atlantic. This was a recognised route, being used by some Dutch East India Company ships in the seventeenth and eighteenth centuries, by the Torrens when Joseph Conrad was first mate, and once John Galsworthy went that way on the same ship when he was on a health trip.32

Being trades, these are more or less continuous year-round. People from Indonesia could pick them up and reach Madagascar, but getting back in the same latitude was near enough to impossible. To do this they would have had to head further south, to 40 or even 50° S, where 'The wind has a fetch that goes round the world in the southern Indian Ocean, unchecked by any land.'33 This was the place for a wild, fast passage eastwards, where winds could reach 70 knots in the winter. Villiers said that these westerlies in the roaring 40s and fearsome or screeching 50s could blow a square rigged ship from the Cape to Australia, 6,000 miles, in three weeks or less. He did it in the well-named Joseph Conrad in the mid 1930s, 'I raced from off Good Hope to off the Leeuwin in less than three weeks, the little ship sometimes almost flying before the shrieking squalls. How the wind and sea could play down there! This was their home, this wild reach of the Indian Ocean where the wind and sea have almost uninterrupted rule all round the world'.34 This is not for the faint hearted. Kay Cottee, sailing alone around the world some years ago, went below 40° S, and had winds of 40–65 knots with continuous huge southern ocean swells and waves of 18 metres. The strength and predicability of these winds can produce strange results. Alan Villiers tells of one voyage from Melbourne to Bunbury, on the Western Australian coast, a voyage of about 3,000 miles. Once the barque Inverneil got out into the Great Australian Bight the captain found the westerlies so strong that he gave up and simply headed east right around Cape Horn, the Cape of Good Hope, and so to Bunbury.35

Apart from winds, there are also broader climatic changes which have substantially affected the Indian Ocean. Even something as apparently fixed and immutable as the sea level can change over time, true very long time, as a result of climatic change. Some 15,000 years ago the sea level was about 100 metres lower than it is at present, and even only 10,000 years ago it was still some 40 metres lower. The Gulf was more like a river than a sea channel. Australia and New Guinea were linked, and the passage from Sundaland to the north was only a short one, though a claim that one could go from one place to the other dryshod is an exaggeration.36 Between 8,000 and 6,000 years ago the sea rose dramatically, in some places by 100 or even 150 metres. Then change slowed or stopped completely. Since the maximum transgression of the middle of the fifth millennium BCE, sea levels overall have fallen by a global process known as eustatic adjustment, but not by enough to affect history very much, and not uniformly.37 At present we are witnessing what seems to be a new and very major change in sea levels, the first significant one for some 7,000 years. Low-lying Indian Ocean islands are threatened with being submerged as global warming raises sea levels comparatively precipitously.

Rainfall distribution could produce major consequences, another example then of a deep structural element impacting decisively on humans. We know something of the little ice age in the seventeenth century in Europe, but this seems to have been a worldwide event. Rainfall data from Java, based on tree rings in teak forests, show that the first three-quarters of the seventeenth century were very dry. The consequences could include drought, and so famine, as in India in the early 1630s, less flooding in the delta areas and so less fertile soils, and possibly a slight drop in the sea level.38

Three other deep structure matters affected travel by sea. First are ocean currents, which experienced sailors can 'read' and use to their advantage. Generally speaking, the earth's rotation along with winds means that it is in the western parts of the huge circulating gyres that currents are strongest. In other words, currents are more of a problem, or opportunity, off the East African coast than elsewhere. During the northeast monsoon, November to April, a weak counter-clockwise gyre produces a westward current that travels as fast as one knot. It hits the coast of Somalia and then turns south, and then east between 2 and 10° S. During the time of the southwest monsoon this current reverses, going east, and then north along the coast of Somalia, where it becomes the strong Somali Current. The situation below the monsoon zone is quite different. Here, south of 10° S, is a steady anti-cyclonic gyre, which means the South Equatorial Current flows west between 10 and 20° S, and divides at Madagascar. One arm goes north of Madagascar, and then south between Madagascar and Africa. The other branch goes south to the east of Madagascar and then curves back to the east towards South India. The first branch is known as the Lagullas or Agulhas current, and Marco Polo claimed that this meant Muslim sailors never went south of Madagascar, or even Zanzibar, because they thought the current meant there was no way to return to the north.39 Lobo, when his ship had trouble getting around the Cape, claimed that if it had kept closer to land in southeast Africa they could have made good progress as the Agulhas current between Madagascar and the East African coast was so strong that it would carry a ship to the south even when the winds were contrary.40 In April 1811 Mrs Graham was on a navy frigate off southeast Africa at about 32° S. It was very stormy:

On the 7th the weather gradually moderated, the sea went down, and we had fine weather; so that though we seemed to have made but little way, the current, which had been checked on the 6th by the contrary wind [that is the southwest monsoon], returning to its usual course with impetuosity, carried us ninety-three miles to the southward of our reckoning in twenty-four hours.41

The combinations further north could produce problems. In 1592 James Lancaster was in Zanzibar, and wanted to go northeast to Kanya Kumari (Cape Comorin) to take prizes. He left in February, but was carried by a very strong current and winds from the northeast and east, towards the north and west, and ended up near Socotra. Then the wind went to northwest and they got around Ceylon in May 1592, just in time to avoid the monsoon from the southwest.42 If one ignored the wind/current combination things could go badly astray. In March 1604 Pedro Teixeira left Hurmuz to sail north to Basra. His ship was foiled by inclement weather, lack of provisions, strong currents, and (predictable for this time of year) contrary winds. After five weeks spent being battered in the Gulf, they returned to Hurmuz.43

Two final deep structure geographical matters could also affect how and when one travelled. Tides can be an extreme hazard in narrow waterways like the Red Sea and Gulf. The effects of the tides in the latter can be felt 100 miles up the Shatt al Arab and into the actual Tigris river.44 In estuaries and deltas this problem is exaggerated. In the Gulf of Cambay the tide purportedly travelled as fast as a man on horseback, and this, combined with silting, led to the decline of the port of Cambay at the head of this gulf. The approach to Kolkata up the Hugli has always presented a daunting challenge to mariners. In northwest Australia the tidal flow is ten metres or more, a hazard for ignorant seafarers and unwary picnickers.

Finally waves. We have described some huge ones in the far south, though some of these may have been exaggerated by excited sailors. Waves higher than 25 feet from trough to crest are rare in any ocean, but storm waves may be twice as high, or even more. Kay Cottee and other voyagers in the Great Southern Ocean experienced these.

Waves beating on a lee shore can make difficult approaches to poor harbours, or coasts where there are no harbours. We pointed out that the west coasts of India and of Malaya, when they are lee shores, are almost unapproachable in a sailing boat. Off the East African coast this is less of a problem, as small ships can go through gaps in the coral reefs which line the coast as far south as Maputo and then approach the land in calm waters. The east coast of India, the Coromandel coast, has a perilous combination of more or less constant high surf and no harbours of any merit. Mrs Kindersley in Chennai wrote to a friend in June 1765, 'I am detained here by the tremendous surf, which for these two days has been mountains high: and it is extraordinary, that on this coast, even with very little wind, the surf is often so high that no boat dares venture through it; indeed it is always high enough to be frightful.'45

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