Treasure Island, also known as Mindemoya, is a large island in Lake Mindemoya, on Manitoulin Island, which is in Lake Huron. As Manitoulin's largest island, it is said to be the world's largest island in a lake on an island in a lake. The island has no permanent residents, but there are some cottages. Treasure Island lies at an elevation of 200m above sea level, with its highest point being about 225m above sea level. It is about 1.4 km in length and about 400 meters wide and about 110 acres.