Practical Guide to Changuu Island Tortoises and Ruins

Prison Island, known locally as Changuu, lies approximately 5.6 kilometers northwest of Stone Town and serves as the primary sanctuary for Aldabra giant tortoises. Visitors typically pay between 30,000 and 40,000 Tanzanian Shillings for a private boat return trip, which takes roughly 25 minutes depending on sea conditions. The island measures about 800 meters in length and just 230 meters at its widest point, making it small enough to explore entirely on foot within a single morning.

Most travelers head straight to the fenced tortoise enclosure upon arrival, but visiting the crumbling prison ruins first allows for a much quieter experience before the mid-morning boat crowds arrive from the mainland. The contrast between the dark historical architecture and the bright turquoise waters of the Zanzibar Channel provides a striking visual record of the island's shifting identity over the last century.

The Evolution from Quarantine Station to Wildlife Sanctuary

British Colonial Construction and the Yellow Fever Era

The island was originally owned by an Arab slave merchant who used it as a detention site for rebellious slaves before they were sold at the Stone Town market. In 1893, the British First Commissioner, Lloyd Mathews, purchased the land to construct a formal prison complex. Although the heavy stone walls and iron-barred cells were completed by 1894, the facility never housed a single criminal. Instead, the administration repurposed the buildings to combat the threat of infectious diseases affecting East Africa's primary port.

Ships arriving from infected regions were diverted here to undergo a mandatory two-week isolation period. This quarantine station specifically targeted yellow fever, which regularly swept through the sailing routes of the Indian Ocean during that era. The original hospital wing and laundry facilities still stand today, though many sections have been reclaimed by thick vines and coastal erosion. Walking through the abandoned cells, one can see the names and dates scratched into the plaster by sailors who were waiting for clearance to enter Zanzibar.

Aldabra Giant Tortoise Conservation Efforts

In 1919, the British Governor of the Seychelles sent four Aldabra giant tortoises to Changuu as a gift to the government of Zanzibar. This small group thrived in the shaded coral rag environment and eventually grew into a population of over 100 individuals. These reptiles are not indigenous to Tanzania, but the island has become one of the most successful breeding centers for the species outside of their native atoll. Some of the oldest residents are estimated to be 196 years old, with their ages painted in blue on their shells for identification.

Handlers provide bundles of leafy greens for visitors to feed the tortoises, but it is wise to be cautious of their powerful beaks during the interaction. The enclosures are divided by age, with a separate nursery area for hatchlings that are vulnerable to predation by the island's resident crows. Watching a 200-kilogram tortoise stretch its neck for a piece of kale remains a slow-motion highlight of the trip. I suggest arriving before 10:00 AM to see the tortoises at their most active, as they often retreat into the deep shade or mud wallows once the equatorial sun reaches its peak.

Navigating the Island Experience and Logistics

Boat Transfers and Entry Requirements

Reaching the island requires hiring a traditional wooden dhow from the beachfront near Forodhani Gardens or the Tembo House Hotel. Rather than booking through a large tour agency, negotiating directly with a boat captain on the sand usually results in a more flexible schedule and a lower price. A fair rate for a private return trip is approximately 25 USD for the entire boat, regardless of whether you are a solo traveler or a group of four. The captains typically wait at the island's pier for two to three hours while you explore the grounds.

Upon landing, you must pay a separate entry fee at the small ticket booth located at the end of the wooden boardwalk. This fee currently stands at 12,000 Tanzanian Shillings or roughly 5 USD per person. Cash is the only reliable form of payment here, so carrying local currency is essential to avoid poor exchange rates offered at the gate. The wooden bridge that leads from the pier to the island is quite narrow and lacks handrails in some sections, requiring careful footing during high tide when the waves can spray over the planks.

Snorkeling and Coastal Geography

The western side of the island features a small sandy beach that disappears almost entirely during high tide. This area is the best spot for swimming, though the current in the Zanzibar Channel can be surprisingly strong. Directly offshore, a fringe of coral reef provides a habitat for starfish, sea urchins, and small tropical fish. While most boat captains offer to rent snorkeling masks and fins for 2 USD, the quality of this equipment is often poor and the hygiene is questionable. Bringing your own gear ensures a better fit and clearer visibility when exploring the shallow reef.

Beyond the tortoises and ruins, the island is home to a colony of peacocks and a small, shy species of antelope known as the Duiker. These animals often hide in the dense scrub forest in the center of the island and are rarely seen by the large tour groups that stick to the main paths. If you walk toward the northern tip of the island, the terrain becomes more rugged with jagged coral stone formations. This area offers a clear view across the water to Stone Town, providing a unique perspective on the city's historic waterfront and the large cargo ships anchored in the deep water channel.

Frequently Asked Questions

What is the total cost for a day trip to Prison Island?

A standard visit costs approximately 12,000 TZS for the entry fee plus a negotiated boat fee of around 30,000 to 40,000 TZS for the return trip. If you choose to rent snorkeling gear or purchase snacks at the small onsite restaurant, you should budget an additional 10,000 TZS per person.

How old are the oldest tortoises on Changuu Island?

The most elderly Aldabra giant tortoises on the island are currently estimated to be between 192 and 196 years old. You can identify their approximate ages by looking for the blue numbers painted directly onto their carapaces by the sanctuary staff.

Can I stay overnight on Prison Island?

Yes, the island houses the Changuu Private Island Paradise Resort, which occupies the former quarantine buildings and several private cottages. Overnight guests have the advantage of visiting the tortoise sanctuary at sunrise before the first public boats arrive from Stone Town at 9:00 AM.

What is the best time of day to visit the island?

Departing from Stone Town by 8:30 AM is ideal to ensure you arrive just as the gates open and before the heat becomes oppressive. The afternoon boats often face choppier waters during the return trip, which can make the 25-minute journey uncomfortable for those prone to seasickness.