The most rewarding short trip is to Bagamoyo, the old slave-trading port 75 km north up the coast — a day there gives you ruined Arab tombs, a German colonial seafront, and the lively Catholic mission museum that traces the slave trade and missionary era. Closer in, Bongoyo and Mbudya islands are reachable by boat from the Slipway or Kunduchi for snorkelling and grilled-fish lunches. To the south, the Kigamboni ferry crosses to a string of empty beaches at Gezaulole and Kipepeo. For a longer day, the Zanzibar ferry takes about two hours and makes a feasible (if rushed) overnight.