Off the coast, there’s Prison Island to visit, also known as Changuu. Located about 30 minutes by boat from Stone Town, it used to be a quarantine station for people visiting Zanzibar. A prison did follow, in 1893, and while a look around its ruins is definitely worth it, the true draw is the chance to see tortoises, and the shy Duiker: a type of tiny antelope. There are no public ferries here, but tours can usually be arranged through your hotel.