Prison Island and Nakupenda: the island that never held a prisoner

This is the most-sold boat day on Zanzibar. There are 54 offers in the current stock with Prison Island or Changuu in the title, from €10, and between them they carry 7,056 reviews – more than any other single outing on the island.

It is also the one where the price you see is least likely to be the price you pay, and where the second half of the trip depends entirely on the tide.

The name is wrong twice over

Changuu is a strip of land about 800 m long and 230 m across at its widest, half an hour by boat off Stone Town. Lloyd Mathews, the British First Minister of Zanzibar, bought it from its Arab owners on behalf of the Zanzibar government in 1893 and had a prison complex built. The buildings were finished in 1894 and never held a single prisoner. In 1923 the island was officially renamed Quarantine Island, and the cells became a hospital where passengers arriving by sea – yellow fever was the fear, and the ships came in between December and March – were held for a week or two before being let through.

So the “prison” you walk around was a quarantine ward. Your guide will say this, and the listings mostly do not.

The part the name does not advertise is older and worse. In the 1860s the Sultan gave the island to two Arab traders, who used it to hold enslaved people before shipping them on. That is the actual prison history of Changuu, and it is one building and one century removed from the ruin you are photographing. If you want that history properly told, it belongs to the mainland and to the former slave market in town – see Stone Town on foot.

The tortoises, and the number that tells the real story

The Aldabra giant tortoises are why the island is on every itinerary. They are not native. The governor of the Seychelles sent four of them here in 1919, and they bred.

The population figures since are the most interesting thing on the island:

• around 200 animals by 1955
• about 100 by 1988
• 50 by 1990
• 7 by 1996

Eighty hatchlings were then brought in from the Seychelles, and 40 of those are recorded as having disappeared. By 2000 the colony was back to 17 adults, 50 juveniles and 90 hatchlings. What the record does not do is apportion the decline between old age, disease and theft – but tortoises do not walk off an island, and the restocking, the fence, the gate and the fee all arrived in the same decade as the low point.

Knowing that changes the visit. A hand-written number is painted on many of the shells; it is a register, not decoration. The oldest animals here predate every building you can see from the jetty.

Most tours include feeding them. That is normal practice at this sanctuary and the animals are habituated to it, but it is worth going slowly – an adult Aldabra can weigh well over 100 kg and has no reason to hurry out of your way.

The fee that half the listings leave out

This is the one thing to settle before you book.

Changuu-Bawe is one of Zanzibar’s designated marine conservation areas, and the Ministry of Blue Economy and Fisheries, through its Department of Marine Conservation, issued a public notice revising the tariff with effect from 1 September 2025: non-East African visitors pay USD 10 per adult and USD 5 per child, non-East African residents of Tanzania USD 5 and USD 3, East African citizens TZS 5,000 and TZS 2,500, and children under five go free. That is charged per person, at the island, on top of whatever you paid for the boat.

The most-reviewed trip that runs only these two stops – 1,084 reviews, 4.1 stars – spells it out in its own small print: “Not all options include the entrance fee and taxes. Please make sure to choose the option that is most suitable for you.” Its inclusion list reads “entry fees (if option selected)”, which is the same sentence wearing a tie.

Not one of the 54 Changuu offers says in its title that entrance fees are included; across the whole stock of 440 offers exactly four do, and none of them goes to this island. So a €10 boat trip and a €26 boat trip are often the same boat, and the difference is whether you hand over dollars at a desk or not. Compare inclusions, not headline prices, and bring cash in small notes.

There are 137 island and sandbank trips from €10 at island tours.

Nakupenda only exists at low tide

Nakupenda is Swahili for “I love you”, and the sandbank named after it is not land. It is a bar of sand that surfaces as the tide falls and goes back under as it rises. At low water it is a bright white crescent you can walk around in ten minutes. Near high water on a spring tide there may be almost nothing above the surface.

No operator controls this and almost none of them explain it. What you can do is ask, before you book, what state of tide your departure is timed to – any Stone Town operator knows the day’s tides, and a good one will tell you which slot to take rather than sell you the one that suits their boat.

The same tide governs the snorkelling. The water off the bar is shallow and warm, and on a slack low tide it is clear; on a run of tide it is not.

What a day actually looks like

Take that offer as the template. It is filed under a three-hour duration, and its own notes say the activity runs 9.30am to 4pm – roughly 25 minutes under sail each way, two hours on Changuu with the tortoises and the ruin, then the crossing to the sandbank, the barbecue lunch on the sand, and snorkelling gear if you want it. Drop-off is back at the Old Fort or Livingstone Beach.

Read the duration field with suspicion on this route generally. Three hours and six and a half hours are both sold under “Prison Island and Nakupenda”, and the three-hour versions are the ones that skip one of the two stops.

Two practical notes worth more than any packing list:

Life jackets. The template offer lists one as included. A verified reviewer in August 2026 reported that none was handed out and advised weaker swimmers to arrange their own. It is a fair thing to ask about at the jetty rather than discover offshore.

Shade. These are open dhows and an exposed sandbank with no trees on it at all. The sun reflects off white sand and shallow water from below as well as above.

Is it worth it?

Yes, with one honest caveat: this is a sightseeing day, not a wildlife day. The tortoises are a managed collection, the reef off the sandbank is a shallow fringe rather than a serious dive site, and you are sharing both with a lot of boats.

If you have one boat day and you want reef, spend it further north. If you have one boat day and you want the view that made you book Zanzibar in the first place – the dhow, the sandbar, the water going three shades of blue in fifty metres – this is that day, and it is the cheapest of the big-name outings.

The 88 snorkelling trips from €10 are at snorkelling, and how this fits with everything else on the island is in what to see in Zanzibar.