Which Great Lake has the highest average elevation above sea level?

Lake Superior has the highest average elevation above sea level of the Great Lakes.

Its surface is about 183 metres above sea level. Water then descends through the St. Marys River to Lake Huron, whose surface is about 176 metres above sea level. This step-down pattern continues through the lower Great Lakes toward the Atlantic Ocean.

Lake Superior’s elevated position is part of the connected Great Lakes–Saint Lawrence system. Locks and canals are necessary in places where rapids, waterfalls, or elevation differences interrupt navigation. The Soo Locks are the major navigation link between Lake Superior and Lake Huron.

Elevation is different from depth and surface area. Lake Superior is both high in the system and very deep, but those are separate measurements. Lake Ontario, at the eastern end, has the lowest surface elevation of the five Great Lakes.