Mangroves are one of the most productive habitats on earth. When exposed at low tide the forests teem with crabs, worms and snails, many of which provide a meal for the birds which gather here.

At high tide mangrove forests attract hundreds of species of fish, crabs and shrimps which swim among the submerged branches and depend on the forests as feeding areas and nursery grounds for their young. The best-developed forests occur around river mouths where they are important in trapping river sediments that would otherwise be washed out to sea.

Kenya has a total area of mangrove of about 53,000 ha (530km²) and Tanzania, with a total of 133,000 ha (1,330km²) also contains the largest continuous mangrove forest of 53,000 ha in the Rufiji River delta. Mozambique has by far the largest mangrove area in the region with 500,000 ha (5,000km²) scattered along its 2,800km coastline, and the South African coastline supports a smaller extent of mangrove, the southernmost forests of the continent.