Osea Island

Osea Island (Historically Osyth or Osey) is an inhabited island in the estuary of the River Blackwater, Essex, East England. It is approximately 380 acres (1.5 km2) in size and is connected to the north bank of the river by a causeway, covered at high water.

Northey Island lies about a mile to the west and Mersea Island is about five miles to the north east.