Sea or town
Dolphins, Prison Island and Kwale are done by boat, and the Stone Town visit is on foot. That first decision already narrows the choice to one or two options.
How long the day takes
Stone Town takes about 3 hours, dolphins 4 to 5 hours, Prison Island about 8 hours and Kwale about 9 h 30. If you want to keep the rest of the day free, the walking visit or the dolphin trip are the shortest.
What you get to see
Dolphins and snorkelling at Mnemba depend on conditions at sea. Prison Island adds giant tortoises and Nakupenda beach, and Kwale adds mangroves, a baobab and a seafood lunch. Stone Town brings history and architecture, listed by UNESCO.