Mnemba Island, 2 miles (3.2km) to the north-east of the island of Zanzibar (Unguja), is surrounded by a vast coral reef measuring several miles in diameter.

Listed as a marine reserve, it is the most popular snorkeling spot in Zanzibar. Moorish idols, blue tang and clownfish are easy to see in a few feet of water, above a colourful, well-preserved reef.