Tumbatu Island is the third-largest island making up Zanzibar, part of Tanzania in east Africa. The island is located off the northwest coast of Zanzibar's main island, Unguja. The island is eight kilometres (5.0 miles) long and is surrounded by a reef, making it somewhat isolated from the rest of Zanzibar, even though its southern shore is only two kilometres (1.2 miles) from Mkokotoni on Unguja. The wedge-shaped island is approximately eight kilometres (5.0 miles) in length, but only two kilometres (1.2 miles) wide at its widest point (in the south).