The Salton Sea is a shallow, saline, endorheic rift lake located directly on the San Andreas Fault, predominantly in California's Imperial Valley. The lake occupies the lowest elevations of the Salton Sink in the Colorado Desert of Imperial and Riverside counties in Southern California. Like Death Valley, it is below sea level. Currently, its surface is 226 ft (69 m) below sea level. The deepest area of the sea is 5 ft (1.5 m) higher than the lowest point of Death Valley. The sea is fed by the New, Whitewater, and Alamo rivers, as well as agricultural runoff drainage systems and creeks.

The Sea was created by a flood in 1905, in which water from the Colorado River flowed into the area. While it varies in dimensions and area with fluctuations in agricultural runoff and rainfall, the Salton Sea averages 15 mi (24 km) by 35 mi (56 km). With an average area of roughly 525 sq mi (1,360 km²), the Salton Sea is the largest lake in California. Average annual inflow is 1,360,000 acre·ft (1.68 km³), which is enough to maintain a maximum depth of 52 ft (16 m) and a total volume of about 7,500,000 acre·ft (9.3 km³).