The Seneca Lake AVA is an American Viticultural Area around Seneca Lake in Upstate New York. The wine appellation is entirely contained within the larger Finger Lakes AVA, and includes portions of Ontario, Schuyler, Seneca, and Yates counties. Seneca Lake is a glacial lake about 35 miles (56 km) long and up to 600 feet (180 m) deep. The lake does not freeze in winter, and acts as a giant heat storage unit for the vineyards surrounding the lake, extending the growing season. The most commercially important grape variety in the region is Riesling, although a wide variety of Vitis vinifera and French hybrid grapes are grown.