Oneida Lake is a large lake in central New York, northeast of Syracuse. The lake is near the Great Lakes and serves as one of the links in the Erie Canal. It empties into the Oneida River which flows into the Oswego River which in turn flows into Lake Ontario. It is named for the Oneida tribe of the Iroquois, who lived in the area until the 1820's when they removed to Wisconsin. While not included as one of the Finger Lakes, it is sometimes referred to as their "thumb".

The current lake is about 21 miles (33km) long and about 5 miles (8.7km) wide with an average depth of 22 feet (6.4m). The shoreline is about 55 miles (88km). Portions of six counties and sixty-nine communities are in the watershed.

Oneida Lake is a remnant of Lake Iroquois, a large prehistorid lake formed when glaciers blocked the current outlet of the Great Lakes, the St. Lawrence River.

The Erie Canal, when first constructed, did not include the lake, but later reconstruction in 1916 included the lake as part of the canal.