Three classic day trips run from Stone Town and are best booked at your hotel the day before.
The Spice Tour takes you out to the plantations north of town to smell, taste and crush cloves, cinnamon, cardamom, vanilla, nutmeg, lemongrass, ginger and the dozen other crops that gave Zanzibar its trading wealth. Lunch is usually a traditional Swahili meal at a farmhouse. Half a day is enough; the full-day version adds a beach stop.
Prison Island — properly Changuu — is a thirty-minute boat ride from Forodhani, with the ruins of a never-used Arab slave-holding station, a small beach, and a sanctuary of giant Aldabra tortoises imported from the Seychelles in the 1920s. The largest are over 150 years old.
Jozani Forest, an hour south by road, is the only home of the endemic Zanzibar red colobus monkey — bright russet, white-bibbed and now seriously habituated to visitors. The forest itself is small, but the monkeys are guaranteed and the walk includes a boardwalk through mangroves.