Prison island, also known as Changuu island, is a half-day excursion in Zanzibar. The name “prison island” came after this distinctive island was used by several sultans of Zanzibar to keep disobedient slaves. The boat voyage takes around 25 to 30 minutes (motorised). You will be able to swim, snorkel, and take pictures with giant tortoises while on this island. You will undoubtedly enjoy a delightful swim, as well as the wonderful snorkeling that will allow you to see the colorful school of tropical fish such as black snapper, orangelined tiggerfish, spotted garfish, barracuda, longfin bannerfish, emperor engelfish, rabbitfish, clown tiggerfish, bluestripe snapper, and others. This day excursion is ideal for snorkelers and beachgoers both, but there is also plenty to see and do, such as historical landmarks and gigantic tortoises.