The Adirondack Mountains form a massif in northeastern Upstate New York, which is part of the United States. Its boundaries correspond roughly to the boundaries of Adirondack Park. They cover about 5,000 square miles. The mountains form a roughly circular dome, about 160 miles in diameter and about 1 mile high. The current relief owes much to glaciation. There are more than 200 lakes around the mountains, including Lake George, Lake Placid, and Lake Tear of the Clouds, which is the source of the Hudson River. The Adirondack Region is also home to hundreds of mountain summits, with some reaching heights of 5000 feet or more.