As Mafia is a small island, the sea plays a major part in the lives of most of its inhabitants. People travel by boat to the mainland and boats are also used for fishing. There are several different kinds of boats, all still made locally:
- Large dhows (jahazi, plural majahazi) with lateen sails, capable of long-distance travel
- Smaller sailing boats (mashua) used for fishing for and carrying goods and passengers to the mainland
- Out-rigger canoes (ngalawa) which may also use sails for in-shore fishing
- Canoes with no out-rigger (tumbwi, plural matumbwi) also used for inshore fishing
- Boats with outboard engines (boti, pl. maboti), many with iceboxes or fridges used to carry fish to Dar es Salaam
People also use the resources of the sea without boats: collecting crabs and other shore-dwelling creatures, and, in some parts of Mafia, cultivating seaweed for sale. Another product which has a long history is the collection and sale of sea cucumbers (jongoo) to Chinese merchants.
