Mafia Island ("Chole Shamba") is part of the Mainland Tanzanian. Many people and even tourism companies abroad confuse about Mafia where most of them think it belongs to the Zanzibar archipelago.

According to the 2002 Tanzania census, the population of the Mafia District was 40,801. The economy is based on fishing, subsistence agriculture and the market in Kilindoni. The island attracts some tourists, mainly adventure scuba divers, game fishermen, and people wanting relaxation.

The Mafia archipelago consists of one large island (394 km²) and several smaller ones. Some of the smaller ones are inhabited, such as Chole Island (2 km²), with a population of 1415. Chole Bay, Mafia's protected deep-water anchorage and original harbour, is studded with islands, sandbanks and beaches. The main town is Kilindoni. The stretch of water between the deltas of the Rufiji River and the island is called Mafia Channel. The popular rumours of pygmy hippo on the island were confirmed by the Tanzania Tourist Board in 2013 because of the first documented sighting by two tourists

Mafia island has a tropical climate. This climate is classified as "Aw" by the Köppen-Geiger system. The average temperature in town of Kilindoni is 26.7°C (78°F). The average annual rainfall is 1,705 mm. The monthly average temperatures are usually between 24.8 - 28.3°C (77°F - 83°F). There is one major rain season, with most rainfall coming between March and May. Dry season spans between July to October