Which Great Lake contains the deepest point in the Great Lakes system?

Lake Superior contains the deepest point in the Great Lakes system.

Its deepest measured point is about 406 metres (1,333 feet) below the lake surface. That depth is in the eastern part of the lake, near the border between Canada and the United States. Lake Superior’s basin was carved and deepened by repeated glacial advances during the Ice Age.

The lake’s great depth helps keep its water cold, and some deep water remains close to 4°C even during summer. Although Lake Ontario is also very deep, reaching about 244 metres, it does not approach Lake Superior’s maximum depth. Lake Michigan and Lake Huron are deep as well, while Lake Erie is much shallower.

Maximum depth is different from average depth and total volume. Lake Superior has the greatest maximum depth, while other Great Lakes lead different rankings. Those distinctions explain why statements about the “deepest,” “largest,” or “most water” lake must specify the measurement being used.