Prison Island, officially named Changuu Island, sits serenely in the turquoise Indian Ocean just 5.6 kilometres northwest of Zanzibar's Stone Town. Originally earmarked as a detention facility for rebellious slaves in the late 19th century and later used as a quarantine station during the colonial era, the island's dramatic history now gives way to one of Zanzibar's most beloved day-trip destinations.

The island's greatest living attractions are its resident giant Aldabra tortoises — a gift from the British governor of the Seychelles in 1919. Today, more than a hundred of these gentle giants, some over a century old, roam freely in a dedicated sanctuary. Visitors can hand-feed and photograph the tortoises up close, making it a particularly memorable experience for families and wildlife lovers.

Beyond the tortoises, Prison Island is fringed by vibrant coral reefs teeming with tropical fish, making it a superb snorkelling destination. The clear, warm Indian Ocean waters and a small but beautiful beach invite swimming and relaxation. The crumbling ruins of the old quarantine hospital and the original slave holding cells add a layer of historical intrigue, providing vivid context to Zanzibar's complex Swahili coast heritage.