Clear Lake is the largest natural freshwater lake entirely in California, and has the largest surface area of any freshwater lake entirely in California, the tenth largest by capacity. It is located in Lake County and is fed by runoff flowing into many streams as well as springs in Soda Bay. Its sole outlet is Cache Creek. There is a dam on Cache Creek to increase the lake's capacity and to regulate outflow.

Clear Lake is 19 mi (31 km) by 8 mi (13 km) at its widest point, with surface area of 43,785 acres (17,719 ha) and a 1,155,000 acre·ft (1,425,000 dam³) capacity. Average depth is 27 ft (8.2 m), maximum is 60 ft (18 m), lake elevation is 1,329 ft (405 m), average water temp is 40 °F (4 °C) in winter and 76 °F (24 °C) in summer.

With over 100 miles (160 km) of shoreline, Clear Lake is a popular spot for watersports enthusiasts. Fishing, swimming, sailing, wind surfing, waterskiing, boating, and riding personal water craft are all popular activities, primarily in the summer. There are 11 free boat launch ramps around the lake that are open to the public. Individuals may rent boats and personal water craft from many businesses around the lake.

Clear Lake is sometimes called the "Bass Capital of the West." Largemouth bass, which are farmed and planted in the lake by California Department of Fish and Game, crappie, catfish, bluegill, and rainbow trout can be found in the county's lakes. Fishing boats can be rented, and many stores and facilities around the lake specialize in fishing equipment. Numerous fishing tournaments and derbies are held through the year.

The best baits for this lake