Name one significant island located in Lake Ontario.

The Toronto Islands are a significant grouping of islands located in Lake Ontario, just offshore from downtown Toronto. They are notable for their recreational opportunities, beautiful parks, and stunning views of the city skyline. The Toronto Islands are a popular destination for both residents and tourists, providing spaces for activities such as cycling, picnicking, and water sports. Additionally, the islands serve as an important ecological habitat, hosting various species of birds and wildlife. Their proximity to one of Canada's largest cities enhances their importance as a recreational and natural area, making them a key feature of Lake Ontario.

In contrast, while Manitoulin Island is the largest freshwater island in the world, it is located in Lake Huron rather than Lake Ontario. Vancouver Island, situated off the west coast of Canada, and Long Island, found along the Atlantic coast of the United States, are completely unrelated to Lake Ontario.