The term Mayotte (or Maore) may refer to all of the department's islands, of which the largest is known as Maore (French: Grande-Terre) and includes Maore's surrounding islands, most notably Pamanzi (French: Petite-Terre), or only to the largest island.
The main island, Grande-Terre (or Maore), geologically the oldest of the Comoro Islands, is 39 kilometres (24 mi) long and 22 kilometres (14 mi) wide, and its highest point is Mount Benara, at 660 metres (2,165 ft) above sea level. Because of the volcanic rock, the soil is relatively rich in some areas. A coral reef encircling much of the island ensures protection for ships and a habitat for fish. Dzaoudzi was the capital of Mayotte (and earlier the capital of all the colonial Comoros) until 1977. It is situated on Petite-Terre (or Pamanzi), which at 10 square kilometres (4 sq mi) is the largest of several islets adjacent to Maore.
Mayotte is surrounded by a typical tropical coral reef. It consists in a large outer barrier reef, enclosing one of the world's largest and deepest lagoons, followed by a fringing reef, interrupted by many mangroves. All Mayotte waters are ruled by a National marine Park, and many places are natural reserves.