island located in the Meghna River estuary, south-central Bangladesh. The island, some 43 miles (69 km) long and 10–15 miles (16–24 km) wide, is separated from the Hatia Islands to the east by the Shahbazpur River, which is an arm of the Meghna River delta, and from the mainland to the west by the Tetulia River. The island is formed of silt carried down by the Meghna River, the strong spring tide (called the bore) of which impinges on the east and floods the watercourses and creeks. The island is often hit by severe cyclones (cyclone) and storm waves. It is connected by regular boat service to the mainland.