Twenty-five minutes by boat from Stone Town, one of the most quietly extraordinary excursions in East Africa is waiting. It involves giant tortoises, colonial ruins, clear Indian Ocean water, and a history more layered than the name lets on.
The boat leaves the Stone Town waterfront and within minutes the city’s carved doorways and minarets are shrinking behind you. The water turns from green to turquoise. A coral-stone island appears on the horizon. You are heading to Changuu Island, better known as Prison Island, and the name is doing the experience no favors. Forget it. What you are actually heading toward is one of the most satisfying half-day excursions in all of Zanzibar; historic, beautiful, unhurried, and home to residents who arrived before the Titanic sank and have absolutely no intention of leaving.
Prison Island, Zanzibar: The Tortoises Have Been Here Longer Than Anyone
The History
The prison buildings were constructed in the late 19th century by Lloyd Mathews, the first minister of Zanzibar under British rule, intended to hold enslaved people in transit before the structure was ever completed. In a telling historical footnote, the prison was never used as one. Instead, British authorities repurposed the island as a quarantine station for yellow fever cases entering East Africa, a role it held into the early 20th century. The name Prison Island outlasted both purposes, which tells you something about how strongly a name can stick even after a place has moved on.
Walking through the ruins today, with an expert guide filling in the details, you feel the weight of that history without it being overwhelming. The island sits at the intersection of the Arab slave trade, British colonial administration, and East African maritime history. That is an enormous amount of story for a small island, and it is exactly why a guided visit is worth far more than an unaccompanied wander.
The Tortoises
And then there are the tortoises. The Aldabra giant tortoises now living in the island’s sanctuary were gifted by the Governor of the Seychelles in 1919, and some of the current residents are believed to be well over 150 years old. The oldest individuals may be approaching 200. To stand next to one and do the mental arithmetic is a genuinely strange experience. The tortoise staring back at you with complete, prehistoric indifference was alive during the First World War. It was alive when Zanzibar was still a British protectorate. It has outlived every political arrangement this island has ever had.
They move at a pace that tells you they have never once been in a hurry, and they are probably right.
They are also, unexpectedly, interactive. You can crouch beside them, observe them being fed, and watch them move with the slow, gravitational confidence of animals that have never needed to run from anything. Children and adults alike tend to go quiet around them. That quality of silence, of being briefly humbled by something ancient and unbothered, is one of the things Prison Island does better than almost anywhere else on the island.
The Water
Beyond the history and the wildlife, Prison Island delivers what every day in Zanzibar should include: clear, warm, Indian Ocean water. The coral areas around the island offer excellent snorkeling, and the shoreline is calm enough for a relaxed swim before boarding the boat back. The views across the channel toward Stone Town, with dhows crossing in the middle distance, are the kind that end up in screensavers. This is not a full beach day, but it is a strong case for why the best excursions in Zanzibar tend to do several things well rather than one thing perfectly.
How to Visit
Prison Island works best as a half-day excursion paired with a Stone Town guided walking tour on the same day, which is exactly how Back to the Source Tours schedules it. The boat departs directly from the Stone Town waterfront, making the logistics effortless. A morning in the city’s alleyways and landmark buildings, followed by an afternoon on the island, covers the full breadth of what Zanzibar’s cultural and historical north has to offer in a single, well-paced day. Attempting to visit from the island’s northern beach zone adds significant travel time and disrupts the natural flow of the excursion.
What to Bring:
- Reef-safe sunscreen; the coral and marine life around the island are protected and worth keeping that way
- Swimwear and a towel; the water around the island is clear and worth getting into
- Comfortable walking shoes for the grounds and historical ruins
- A small amount of cash in Tanzanian shillings for the entrance fee
- A wide-angle perspective on time; the tortoises will reframe it entirely
Prison Island is one of those excursions that tends to exceed expectations precisely because it asks so little of you. No strenuous activity, no complex logistics, no pressure to fill every minute. You arrive, you walk, you listen, you spend time with creatures that have been doing this far longer than you have, and you swim in one of the most beautiful bodies of water in East Africa. Then you take the boat back to Stone Town, which will be waiting for you exactly as you left it, loud and fragrant and entirely itself.
It is, by any honest measure, a strong day.
Prison Island is included in Back to the Source Tours’ 6-day Spice, Sand & Soul in Zanzibar itinerary, paired with a guided Stone Town walking tour on Day 2. Every detail of the routing, timing, and experience has been designed so you arrive informed, relaxed, and ready to let the island do its work.
Plan this experience with Back to the Source Tours: East Africa Tour Packages, East Africa Group Tours, and/or Request Your East Africa Safari Quote.