Prison Island

Prison Island — officially called Changuu Island — sits about 5.5 kilometers northwest of Stone Town and packs an extraordinary amount of history and wildlife into a small strip of coral and forest. The British built a detention facility here in the 1860s, originally intended to hold rebellious slaves and later used as a quarantine station for ships arriving from plague-affected ports. It never actually functioned as a conventional prison for long, but the name stuck, and the ruins of the old holding compound are still visible on the island today.

The real draw now, alongside the history, is the colony of Aldabra giant tortoises that roam freely across the island's grounds. These animals — some of them over a century old and weighing well over 200 kilograms — were gifted to Zanzibar from the Seychelles in 1919 and have been breeding here ever since. You can walk right up to them, hand-feed them greens for a small fee, and generally have the kind of up-close wildlife encounter that feels impossible until it's happening. The surrounding reef is also excellent for snorkeling, with clear shallow water and healthy coral visible just off the beach.

The island is reached by a short dhow or motorboat trip from Stone Town's waterfront — operators cluster around the main ferry port and most visits are sold as half-day packages including boat transfer, entry, and sometimes snorkel gear. Go in the morning when light is better and it's less crowded. The beach and snorkeling are the weak link if you've been elsewhere in Zanzibar, but the tortoises and the melancholy atmosphere of those old stone walls make this genuinely worth the trip.