Changuu Island is a small island about 6 km north-west of Stone Town, Zanzibar. The island is also known as Prison Island. The island was uninhabited until the 1860s when they started a prison on the island for rebellious slaves prior to shipping them abroad or selling them at the slave market in Zanzibar's Stone Town.
In 1919 the British governor of Seychelles sent a gift of four Aldabra giant tortoises to Changuu from the island of Aldabra. These tortoises bred quickly and by 1955 they numbered around 200 animals.