Prison Island (Changuu)
Despite its name, this small island was never a prison for criminals. Discover its layered history as a quarantine station and slave detention center, and meet the island's most famous residents: a colony of gentle Aldabra giant tortoises.
The Island With Many Names
Changuu Island—known to most visitors simply as Prison Island—lies just 5.6 kilometers northwest of Stone Town, a short and scenic boat ride across the Zanzibar Channel . The island earned its nickname from the prison buildings constructed by British First Minister Lloyd Mathews in 1893. But here's the twist: no prisoners were ever housed there. Instead, the facility was converted into a quarantine station for yellow fever cases arriving at East Africa's main port .
The island's history goes back even further. In the 1860s, the first Sultan of Zanzibar gave Changuu to two Arab owners who used it as a detention center for rebellious slaves before they were shipped abroad or sold at the Stone Town market . Today, the old prison ruins and quarantine buildings stand as quiet reminders of this complex past, and your guide will walk you through the stories that shaped the island.
But the true stars of Prison Island are the tortoises. In 1919, the British governor of Seychelles gifted four Aldabra giant tortoises to Changuu. They bred quickly, and by 1955 the population had grown to around 200 . Today, the sanctuary is home to some of the oldest and largest tortoises in the world—many weighing over 200 kilograms and living well past 100 years [citation:2][citation:4]. You can walk among them, feed them, and take photos with these gentle giants.
Tour Highlights
Scenic Boat Ride from Stone Town
Cruise across the turquoise waters of the Indian Ocean with views of Stone Town's coastline. The journey takes around 20–30 minutes by boat [citation:4][citation:9].
Giant Tortoise Sanctuary
Meet and feed the Aldabra giant tortoises, some of which are over 100 years old. Learn about their history, conservation, and how they came to Zanzibar from the Seychelles [citation:2][citation:11].
Historic Prison & Quarantine Ruins
Explore the old prison buildings and quarantine hospital with your guide. Learn the real story behind the island's name and its role in Zanzibar's colonial history [citation:2].
Beach Relaxation & Snorkeling
After the tour, enjoy free time on the island's white-sand beach. Swim in the clear water or snorkel around the coral reef (snorkeling gear can be arranged) [citation:9][citation:11].
Peacocks & Island Wildlife
Keep an eye out for the island's resident peacocks, whose brilliant feathers add a splash of color to the ruins and gardens [citation:4][citation:13].
Experience Prison Island with Zanora
This is a half-day excursion, perfect for travelers who want to combine history, wildlife, and a little beach time without committing to a full day on the water. Your Zanora guide will handle boat transfers, entrance fees, and timing, so you can simply enjoy the island. Note: entrance fees are sometimes paid separately on the day (approximately $12–$22 USD per person), so we'll confirm all details with you before booking [citation:2][citation:4].