Despite the patches of arid land, the African eastern coast is mostly covered by forests, or at least that was the case before deforestation. The coastal strip, the land from the sea to about 200 metres of altitude, is 15 to 65 km wide. At times the strip widens to include large river deltas; other times, the line of the hills comes closer to the coast. Coral reefs are found almost throughout the length of this region, from southern Somalia to northern Mozambique. The climate is tropical with a characteristic rainfall regime dependent on the monsoons. The central portion of the region (Kenya and the Zanzibar Archipelago) enjoys rainfalls up to 1500 mm spread over the year. Away from this area, both total rainfall and its duration diminish into a single rainy season in both directions.
The Swahili and other coastal peoples cleared much of the original rain forest for timber or firewood, and for cultivation. Today, only patches of forests have survived in suitable areas along the entire coast from Malindi in Kenya to Lindi in southern Tanzania and beyond. These forests produce some valuable timber, such as mvule – used in furniture making – and African teak.
During the two millennia B.C., agriculturists occupied a large part of the interior of eastern Africa. They reached the coast where remnants have survived down to the present, including the Dahalo of coastal Kenya and the Ma’a in Usambara. The area was subsequently occupied by Iron-Working cultures who reached the coast in the II century A.D., where they produced pottery known as the Kwale ware. The Periplus, an account written by a Greek speaking traveller around 100 A.D., describes the people of these lands as being agriculturalists who also practiced fishing. They were also involved in trade exchanging ivory, rhinoceros horns, and tortoise shell in exchange for lances, hatchets, swords, and glass beads.
Subsistence agriculture was based on a range of cereals, root crops and beans. Conditions were very favourable for sorghum; rice was cultivated in the river valleys and swampy areas. Bananas were also widely cultivated in these areas both as a food and as a fruit. Cassava, maize and sweet potatoes were introduced after the discovery of America. Oranges and pineapples were introduced from the Mediterranean.
However, the characteristic plant of the coast is the coconut. Almost every part of the tree is put to use to provide timber, fuel and thatch. Coconut milk is used widely by the Swahili to cook their distinctive dishes. Coconut meat is dried to make copra, which can be pressed for oil, used in cooking and making soap, and the residue is good animal fodder. Moreover, the sweet sap can be fermented to make an alcoholic drink. The coconut also occupies a central position in the culture of all the littoral people; for instance, the Swahili sprinkle a newborn baby with coconut water.
Creeks and estuaries are common in the region. Coral reefs follow the coastline and enclose shallow lagoons and bays. Coral provides a supply of lime and rough stone, a common building material all along the coast from at least the X century. The intertidal mud stretches are a good ground for mangroves swamps which yield termite resistant mangrove poles, their wood is also used to produce high-grade charcoal. For centuries, these poles have formed the main bulk commodity for dhows from the East African coast, as well as from India, to Arabia and the Persian Gulf where they were used in the construction of multi-storeyed houses.
The trade in mangrove poles continues today. Kenya produces around 500,000 poles a year, while Tanzania averages 300,000. In the past, when export of these poles was thriving, an average foreign dhow took around 6-7000 poles, which would have employed eighty workers to cut over a month, and small dhows, each with a crew of six to ten men to transport them from the mangrove swamp to the port. Therefore, the export trade in mangrove poles alone would have employed thousands of cutters, sailors, and other workers. When the local demand is also taken into consideration, the total number employed in this industry was considerable.
Because of the narrow continental shelf, fisheries potential is limited along the Swahili coast. Yet, it has provided an essential economic opportunity for those using small craft to fish inshore using fish traps and nets. Where fish stocks allow, like in Zanzibar, Pemba, and Lamu, fishermen follow movement of fish shoals up and down the coast. Women and children also collect edible shellfish, shrimp and crabs, and catch small fish in shallow waters with large rectangular pieces of cloth, while men join in the hunt for squid and octopus on the coral reefs. Fishing is forbidden in some months to allow the regeneration of marine resources.
The sea occupies a central role the life and history of the Swahili. Good productive land has often been a scarce resource; the lack of adequate technology to increase its productivity made agriculture a labour intensive job. Instead, the sea has always been bountiful. It provided subsistence to the coastal community. It was also the means for trade and offered employment to sailors. There is evidence that mangrove poles and cowrie shells have been articles of export from the East African coast for more than a thousand years.
Unlike the land, the sea resisted any tentative of colonization. With the exception of a few fishing areas, sea exploitation remained at a rudimentary stage of harvesting from nature where one had not sowed. Today, the sea is used for communication, tourism, and modern fishing; activities that replicate past use and only intensify it. The danger is now coming from industrial enterprises. Off-shore oil and gas exploitation and inshore rare earth digging carry the risk of pollution of the environment while do not assure the local population with higher earnings. This modified attitude towards the sea will affect Swahili culture and way of living more than the many events happened in history.