Surrounded by the Indian Ocean, Zanzibar archipelago possesses rich marine resources that have been poorly exploited compared to neighbouring coastline on the mainland of East Africa. Its marine habitat consisting of coral reefs, seagrass beds, mangroves and sandy beaches harbours a diversity of vertebrate and invertebrate species. About 25% of the people of Zanzibar depend on fishing and related activities for their livelihood but mostly using traditional fishing gears.
Mangrove forests located on various places on Zanzibar's coastline provide a means for livelihood for a large number of people. Direct harvesting for building materials and collection of firewood from the adjacent coastal thickets are common but according to forest protection laws in Zanzibar, such activities are mostly illegal since all the mangrove forests were declared forest reserves by the colonial administration. However, such laws are difficult to enforce and, strictly speaking, for some communities a life without encroaching the mangroves is next to impossible. For example, in some areas of Pemba island building materials from mangroves and clove trees, both protected by law, are the only easy option for those wishing to build new homes. Beekeeping and crab gathering are also common activities in most mangrove forests of Zanzibar.
Pelagic fish species such as sardines, anchovy and other non-commercial species are abundant in the Zanzibar and Pemba Channels. Crustaceans (crabs, shrimps and lobsters) are found along the shallow waters but offshore fishing of lobsters is very popular among the artisanal fishermen due to higher prices offered by the lucrative tourism industry. Molluscs such as squids and octopuses, clams, oysters, and several types of bivalve species are found. Mackerels, several types of tuna, wrasses, rays, rock cods, sharks, snappers, mullets, eels, and parrotfish are some of the products harvested from surrounding waters. However, commercial fishing using big trawlers is not common in Zanzibar and Pemba Channels but such kind of investment could be considered for the Economic Exclusion Zone (EEZ) in the vast Indian Ocean on the eastern side of both islands.
Recently, farming of red algae has gathered momentum in both Unguja and Pemba at the expense of some traditional coastal activities such as rope making, cockling and shell gathering. The type of seaweed being farmed in Zanzibar, genus Eucheuma, was originally imported from the Philippines. From its first introduction in 1988, farming has expanded from the east coast of Unguja Island to various other coastal localities in both islands.
Other Zanzibar's marine resources include coral reefs, seagrass beds, and sandy beaches. With more than 200,000 sq. km of coral reefs and plenty of seagrass beds, the undersea marine environment is one of the best in East Africa. Capitalizing on the beauty of the reefs, scuba diving has become a popular tourist attraction in Zanzibar. Another marine resouce, which has become iconic for Zanzibar is the availability of crystalline sandy beaches covering an length of about 80 km on both islands.