The Great Lakes of North America form the largest system of surface freshwater on Earth, and their names — Superior, Michigan, Huron, Erie, and Ontario — are remembered by the acronym HOMES. Lake Superior is the largest by surface area at roughly 82,100 km², making it the largest freshwater lake in the world by area, and it is also the deepest of the five with a maximum depth of about 406 meters (1,332 feet). At the other extreme, Lake Erie is the shallowest, averaging only 19 meters (62 feet) in depth. Lake Michigan is the only one of the five that lies entirely within the United States; the others are shared with Canada.
The Great Lakes are connected to one another and ultimately to the Atlantic Ocean through the St. Lawrence Seaway, a vast system of locks, canals, and channels that allows ocean-going vessels to travel inland as far as the inland ports of the Midwest. This artificial extension of the sea has shaped the economies of cities from Duluth and Chicago to Montreal and Quebec, and it is one of the engineering marvels of modern maritime transport.
Beyond the Great Lakes, several inland bodies of water are defined by their extreme characteristics. The Caspian Sea, the world's largest enclosed inland body of water, is bordered by Russia, Kazakhstan, Turkmenistan, Iran, and Azerbaijan, and is often classified as a lake despite its name. The Dead Sea, lying between Jordan and Israel/Palestine, is so salty that its salinity reaches about 34%, nearly ten times that of the open ocean, and its shoreline sits at roughly 430 meters below sea level — the lowest surface elevation on land. The Aral Sea, in contrast, was once a vast lake straddling Kazakhstan and Uzbekistan but has lost most of its water because irrigation projects diverted the Amu Darya and Syr Darya rivers that once fed it.