Sonadia is about seven kilometer from Coxs Bazar and about nine square kilometer in area. The western side of the island is sandy and different kinds of shells are found on the beach. Off the northern part of the island, there are beds of window pane oysters. During winter, fishermen set up temporary camps on the island and dry their catches of sea fish. Every winter thousands of fishermen camp there and make large hauls.  

The island is also known as a paradise for migratory birds like ducks, seagulls, fowls and geese etc. During the winter season migratory birds in swarms are found crowding the beach, marshes and pools of the island