Mwali, also called Mohéli, is the smallest of the islands in the Comoro archipelago with an area of 81 square miles (211 square kilometers). Composed largely of a plateau that averages about 300 metres (1,000 feet) in elevation, the island ends in the west in a ridge reaching more than 790 metres (2,600 feet) above sea level.

The island has rich soil, magnificent forests and fine pasture lands. The valleys and slopes of the island are covered with coconut trees, coffee trees, cacao and ylang-ylang trees, and a wide variety of crops. Three small islets on the south side of the island near the harbor of Nioumachoua provide a natural harbor. In the past, the islet of Shisiwa Unefu was used as a leper colony.

A strong sea swell hampers shipping. Mwali's chief towns are its capital Fomboni on the northern coast, and Nioumachoua.

Mwali has a population of approximately 30,000, making it the least densely populated of the four islands. In September 1997, a group of secessionists declared the island independent of the Comoro Republic but this claim was rejected and Mwali has now agreed to join the Union of the Comoro Islands. A port was built at Fomboni on Mwali in the early 1990s with EU funds.

In April 2001, 404 square kilometere Mohéli Marine Park was established off the southern zone of Mohéli. It is the first protected area within Comoros. It includes beaches and rocky areas, offshore islands, coral reefs and scattered mangrove strands. The pristine waters, beautiful landscape, nesting turtles and regular sighting of whales and dolphins allow Mwali/ Mohéli to develop ecotourism. Properly managed ecotourism has the potential to conserve local resources and benefit the local community.