Which Great Lake has the greatest maximum depth?

Lake Superior has the greatest maximum depth of the Great Lakes.

Its deepest point is about 406 metres below the surface, considerably deeper than any other lake in the system. This depth reflects the lake’s position in a broad, ancient depression shaped by geological processes and later modified by continental glaciers. The deep basin also helps keep Superior’s water cold throughout the year.

Lake Superior’s large volume means that its water takes a long time to circulate and replace. The lake is connected to Lake Huron by the St. Marys River, where the Soo Locks allow ships to bypass rapids and elevation changes near Sault Ste. Marie. From Lake Huron, water continues through the lower Great Lakes toward the Atlantic.

Maximum depth and average depth are different measurements. Superior is deepest on both counts, but its exceptionally large surface area is the more commonly cited reason it is considered the dominant Great Lake by size.