Chautauqua Lake is located entirely within Chautauqua County, New York. The lake is approximately 17 miles (28 km) long and 2 miles (3.2 km) wide at its greatest width. The surface area is approximately 13,000 acres (53 km²). The maximum depth is about seventy-eight feet (23 m).

The water from the lake drains to the south, entering the Allegheny River and the Ohio River, instead of flowing north into the Great Lakes.

At the southern end is the City of Jamestown, New York. The village of Mayville, New York is at the northern end. The lake is used primarily for tourism and recreation, mostly boating and fishing.

There is one bridge that connects the opposite sides of the lake. The bridge travels from Bemus Point, New York to Stow. Additionally, there is a ferry that at one time ran the same course.