Location and directionThe islands of Zanzibar are an archipelago. The largest, Zanzibar, is a low lying stretch of land, crab claw shaped and lying 37 kilometres off the coast of Tanzania. Pemba Island is fifty kms north of Zanzibar Island and is the main source of cloves. Mafia Island is 160 kms south of Zanzibar and is the most southerly and smallest of the main Tanzanian islands. There are also a number tiny islands just off the shores of the main island, such as Chunguu Island (Prison Island), Grave Island, Bat Island and Snake Island.