Searles Lake, Dry lake in San Bernardino County, United States

Searles Lake is an endorheic dry lake in the Searles Valley of the Mojave Desert, about 19 km long and 13 km wide at its widest point. The basin is bounded by the Argus and Slate Mountains, and the mining community of Trona sits on its western shore. The Trona Pinnacles, a tufa formation and National Natural Landmark, rise from the lake bed.

John and Dennis Searles found substantial borax deposits in 1863, sparking commercial mining operations about a decade later. This discovery transformed the area into a significant mining region and drew workers and investment.

The lake's name honours John Wemple Searles, whose San Bernardino Borax Mining Company began producing borax from the dry surface in 1873. A California Historical Landmark plaque at the roadside rest area in Trona marks the borax discovery. The mineral searlesite was first identified here and named after the lake.

Access varies by area—some sections are open to explore while others have restrictions. Wear sturdy shoes since the salt flats have rough surfaces, and expect intense heat during daylight hours.

Searlesite, a rare sodium borosilicate mineral, was first identified at Searles Lake and named after the site. The lake's borax discovery is California Historical Landmark #774, marked by a plaque at the roadside rest area in Trona. Between 1922 and 1928 an Epsom Salts Monorail crossed the lake on a wooden trestle.