The Adirondack Mountains () form a massif in northeastern New York, United States. Its boundaries correspond roughly to the boundaries of Adirondack Park. They cover about 5,000 square miles (13,000 km2). The mountains form a roughly circular dome, about in diameter and about high. The current relief owes much to glaciation. There are more than 200 lakes around the mountains, including lakes George, Placid, and Lake Tear of the Clouds, on Mount Marcy, which is the highest source of the Hudson River.