Which lake contains Manitoulin Island, the world's largest lake island?

Manitoulin Island lies in Lake Huron, making Lake Huron the answer.

Located in Ontario, Canada, Manitoulin is the world’s largest island contained within a lake, covering about 2,766 square kilometres. It sits between the main body of Lake Huron and Georgian Bay, with the North Channel along its northern side.

The island is notable for a geographic nesting trick: it contains more than 100 freshwater lakes of its own. Lake Manitou is the largest of them, while Treasure Island in Lake Mindemoya is an island within a lake on an island within a lake.

Its name comes through French from an Ojibwe or Odawa term meaning “cave of the spirit.” Manitoulin also preserves evidence of Indigenous habitation reaching back roughly 10,000 years, including archaeological finds at Sheguiandah.