A few kilometres from Zanzibar Town are several small islands, some of which are good destinations for a relaxing day's outing. Boat trips to the islands can be arranged with a tour company, or with one of the papaasi (touts) who look for business around town and along the seafront, or direct with one of the boat captains. Costs range from US$15 to US$60 for the boat, or from US$5 to US$20 per person, depending on who you deal with, the number of hours you want, the quality of the boat and whether you're prepared to share with other people or want a boat to yourself. Other factors might be lunch or snorkelling gear included in the price. You can hire a boat for yourself, or reduce costs by getting your own small group together. If you're alone, it's usually easy to link up with other travellers. Boats go across to the islands every morning from the beach by the Big Tree on Mizingani Road (the seafront), from the beach near the Tembo Hotel and the beach opposite the Africa House Hotel.

Changuu island

This island is also called Prison Island, and was originally owned by a wealthy Arab who used it as a detention centre for disobedient slaves. After the abolition of slavery, in 1873, the island was bought by general Lloyd Mathews, commander of the sultan's army, who built a house here. In 1893 a prison was built on the island, but it was used instead as a quarantine station for the whole east african region. In the 1920s passengers arriving from India had to spend between one and two weeks on Changuu before proceeding to Zanzibar Town. On some old maps, Changuu is called Kibandiko Island, but this name now seems to be forgotten.

Today, the island is owned by the government and non-Tanzanian visitors must pay a US$4 entry fee (TSh are not acceptable). You can still see the quarantine station, and the house built by General Mathews which is now used as a restaurant. A path leads right round the island (about an hour's easy stroll), also passing some old pits where coral has been dug out to make building stone. Some of these pits fill with water at high tide, and in colonial days they were kept clean and used as swimming pools.

The island's other highlight is the large number of giant tortoises (Geochelone gigantea). Four tortoises were brought from the island of Aldabra in the Seychelles in the 18th century, as a gift from the Seychelles governor to his opposite number in Zanzibar. They started to breed, and by 1955 there were 200, but after independence the numbers began to drop, partly because people started to steal them to sell abroad, either as exotic pets, or as food for 'exotic restaurants'. The numbers dropped to 100 in 1988, then 50 in 1990, until by late 1996 there were only seven left. In the same year a group of 80 hatchlings were moved to Zanzibar for protection – and 40 of them disappeared. Today the tortoises are protected in a large sanctuary compound provided by the Zanzibar government with help from the World Society for the Protection of Animals. In 2000 there were 17 adults, 50 juveniles and 90 hatchlings, all individually identified and protected by microchips injected under the skin. Since then, many more have been brought in, mostly juveniles. You can go into the sanctuary to see the tortoises close up. You can feed them (they delight in fresh mango peel), but please obey the signs and do not lift or sit on the tortoises.

Changuu Island has a small beach, and you can go snorkelling on the nearby reef. A rundown former government guesthouse on the island ceased functioning a couple of years back, but it has been privatised and is likely to re-open in a more upmarket incarnation in the near future.

Chapwani Island

This is also called grave island as a small section of it has been used as a Christian cemetery since 1879. Most of the graves belong to British sailors who were killed fighting against Arab slave ships, including Captain Brownrigg; others date from world war i when the british ship pegasus was bombarded and sunk by the german ship königsberg in zanzibar town harbour. There is a small beach on the island, and a lovely patch of indigenous forest, with a population of small duikers, some massive coconut crabs and a colony of fruit bats, which every evening do a few circuits of the island then zoom off to Zanzibar Town in a dark cloud. There are about 100 species of bird. The island's small exclusive hotel ceased operating in 2003 and it is uncertain when or indeed whether it will re-open.

Snake Island

This is the popular name for the very small island between Changuu and Chapwani islands. Boats do not usually land here as there is no beach.

Bawe island

About 6km directly west of zanzibar town, this uninhabited island is not as frequently visited as changuu, although the snorkelling is reported to be of good quality. The same people who run the boats to changuu will also take you to bawe, either as part of the same trip, or as a separate out-and-back voyage. Prices to bawe are a bit higher than those to changuu.

In the 1870s telegraph cables were brought ashore here, linking Zanzibar with the Seychelles, Aden and South Africa. Another line was run from Bawe Island to the External Telecommunications building in the Shangani area of Zanzibar Town. The old 'Extelcoms' building has now been converted into the Serena Inn, and another hotel is planned for Bawe Island itself. To stay in touch it is thought that they will not use the original phone line …