Lake Manitou is the largest lake on Manitoulin Island in Ontario, Canada. With an area of 104 square kilometres, it is the largest lake on a lake island in the world. Reaching depths of up to 162 ft, it is also the deepest of the 108 lakes on Manitoulin Island. Lake Manitou's depth creates a natural habitat for lake trout and ling, making it a popular fishing destiā¦Lake Manitou is the largest lake on Manitoulin Island in Ontario, Canada. With an area of 104 square kilometres, it is the largest lake on a lake island in the world. Reaching depths of up to 162 ft, it is also the deepest of the 108 lakes on Manitoulin Island. Lake Manitou's depth creates a natural habitat for lake trout and ling, making it a popular fishing destination. Other fish including bass, whitefish, pickerel, and pike are also seen throughout the deep, clear waters. It is drained by the Manitou River.