What is the largest island in a lake in the world?

The largest island in a lake in the world is Manitoulin Island in Lake Huron, Canada.

Manitoulin lies within the Canadian province of Ontario and covers about 2,766 square kilometres. It is the world's largest freshwater island and is large enough to contain more than 100 inland lakes of its own. Lake Manitou, the island's biggest lake, covers about 104 square kilometres.

The island has a long Indigenous history. Archaeological evidence at Sheguiandah indicates human activity dating back roughly 10,000 years, while the name Manitoulin comes through French from an Anishinaabe term associated with a spirit or sacred cave. Today, communities such as Little Current and Manitowaning occupy the island.

The wording can cause confusion because other large lake islands exist, including René-Levasseur Island in Quebec's reservoir and Ometepe Island in Nicaragua's Lake Nicaragua. However, for the standard geographic category of the world's largest island located in a lake, Manitoulin Island is the canonical answer.