Lake Ontario
The smallest Great Lake by area, last before the Atlantic
Lake Ontario is the smallest of the Great Lakes by surface area, about 7,300 square miles (18,960 km²), though it is far deeper than Erie and holds much more water. It sits at the bottom of the Great Lakes staircase, receiving the others' outflow over Niagara Falls and draining out the St. Lawrence River to the Atlantic — the final lake before the chain reaches the sea. It borders New York and the Canadian province of Ontario.
Despite its smaller size, Ontario reaches depths of about 800 feet (244 m) and rarely freezes over completely, its stored heat moderating the climate of the surrounding fruit-growing country. As the gateway between the upper lakes and the ocean, it anchors the eastern end of the St. Lawrence Seaway, the shipping route that lets oceangoing vessels reach deep into the heart of the continent.