The prison that never held anyone
Changuu is a small island about five and a half kilometres north-west of Stone Town, roughly 800 metres long and 230 at its widest, and it is sold everywhere as Prison Island. The name is accurate about the building and wrong about what happened in it.
General Lloyd Mathews bought the island in 1893 on behalf of the Zanzibar government, intending a prison for violent and repeat offenders from the mainland who fell under Zanzibar’s jurisdiction. Cornerstones were laid that July and the buildings were completed in 1894. No prisoners were ever moved there. Zanzibar’s own Department of Museums and Antiquities describes the structure as a prison “which was never used as a prison, but as a hospital and yellow fever quarantine station during the time of the British protectorate”, and the academic account of the site reaches the same conclusion from the colonial record.
So the cells are real, the sentences are not, and a guide describing conditions endured by inmates is describing something that did not happen.
What it was actually used for
Quarantine. After plague broke out in India in 1898 the island became the central quarantine station for the whole of East Africa. The prison was converted into the station’s hospital, and the island was officially renamed Quarantine Island in 1923. A new quarantine complex with capacity for 904 people was built at the south-western end in 1931.
The work was seasonal — ships arrived between December and March, and cases were held a week or two — so the island stood empty most of the year and was used as a health resort by Europeans, with a bungalow built for the purpose in the late 1890s. Old coral-mining pits were cleaned out and used as swimming pools. That is the history the buildings actually carry, and it is a more interesting one than the prison story it is sold under.
An earlier and grimmer use is widely repeated: that the island was given by Sultan Majid in the 1860s to two Arab owners who held rebellious enslaved people there before sale at the Stone Town market. It is plausible and it fits the period, but it could not be traced to a source that stands up, and the academic history of the island does not make the claim. It is set out here as an unverified account rather than as fact. The slave trade history guide covers what is documented about the archipelago’s role.
Visiting
Changuu is government-owned, with accommodation run privately, and it is a gazetted historical site — the antiquities department added Kisiwa cha Changuu to its register in 2002. It sits inside the Changuu-Bawe Marine Conservation Area along with Bawe and Chapwani.
It is the standard half-day from Stone Town and is usually combined with a sandbank stop, covered in the sandbank trips and island hopping guide. There are ruins, a short forest walk, the giant tortoise enclosure, and easy sheltered snorkelling on reef that is in visibly harder-used condition than the protected sites further out. The island is also known as Kibandiko on older maps, and changuu is the Swahili name of a local fish.
Common questions about Prison Island
Were prisoners ever held on Changuu?
No. The prison was completed in 1894 and left unoccupied. Zanzibar’s own antiquities department states plainly that it was never used as a prison but as a hospital and quarantine station.
What were the buildings used for, then?
Quarantine. The island became East Africa’s central quarantine station after the 1898 plague outbreak in India, the prison became its hospital, and it was renamed Quarantine Island in 1923. A complex for 904 people was added in 1931.
Did it hold enslaved people before that?
It is often said that it did, in the 1860s, before sale at the Stone Town market. The claim could not be traced to a reliable source and the academic history of the island does not make it, so this page reports it as unverified rather than as history.
How long does a visit take?
A half day from Stone Town, usually combined with a sandbank. The island is small — about 800 metres long — and the ruins, the walk and the tortoises are done comfortably in a couple of hours.