Prison Island

“Prison Island off Zanzibar never actually held prisoners - its prison became a quarantine station - but it is now home to giant tortoises, some well over a century old.”

About Prison Island

Changuu was used in the nineteenth century to detain enslaved people before sale, part of Zanzibar's brutal slave trade. A prison was later built on the island, but it was repurposed as a quarantine station for infectious diseases such as yellow fever, so it never functioned as intended, leaving the misleading name. The giant Aldabra tortoises were introduced as a gift in the early twentieth century and have bred into the colony seen today, making the island a popular and easy excursion from Stone Town.

Overview Prison Island, officially Changuu, is a small island a short boat ride off Stone Town in Zanzibar, best known for a colony of giant Aldabra tortoises, some well over a century old. Despite its name, the island never really served as a prison; the building erected for that purpose was instead used as a quarantine station for yellow fever cases, and the name stuck.

The Giant Tortoises The island's star residents are the giant tortoises, originally a gift from the Seychelles, which now number in the dozens and roam a sanctuary where visitors can walk among them, feed them and see individuals whose ages are painted on their shells, some born well over a hundred years ago.

A Dark Backstory Before the quarantine era, the island had been used to hold enslaved people, a grim chapter in Zanzibar's slave-trade history that underlies its more benign present.

Beach and Snorkelling Around the tortoise sanctuary and old buildings, the island has a small beach and clear water good for snorkelling, making it an easy half-day trip from Stone Town.

The Experience

A short dhow or motorboat ride from Stone Town brings you to the island, where you can wander the tortoise sanctuary among the huge, ancient reptiles, feeding them leaves and reading the ages painted on their shells. The old quarantine buildings and the island's layered history add context to the visit. Afterwards, the small beach and clear shallows invite a swim and some snorkelling, making Changuu a relaxed half-day escape that combines wildlife, history and the sea.

Why It Matters

Prison Island (Changuu) is a popular Zanzibar excursion notable for its colony of giant Aldabra tortoises and for a layered history that runs from holding enslaved people to serving as a quarantine station rather than the prison its name implies.

Why Visit

It offers a close, memorable encounter with century-old giant tortoises plus snorkelling and history, all a short hop from Stone Town. Walk among the tortoises, swim at the small beach, and learn the island's surprising and sobering past.