Crystal Lake Recreation Area, Protected area in San Gabriel Mountains, California

Crystal Lake Recreation Area is a protected region in the San Gabriel Mountains featuring a natural lake, 16 nature trails, and visitor facilities across the landscape. The site includes 120 camping sites, a visitor center, and a café positioned within the mountain setting.

The area was originally called Pine Flat and Sycamore Lake before receiving its current name in 1887 when Judge Benjamin Eaton observed the water's clarity. This naming reflected an early period of documented recognition and mapping of the location.

The open-air amphitheater is a separate structure from the campground, listed alongside the lake, the roughly 120-site campground and the Deer Flats group campground as one of the area's main facilities. The lake itself was long called Sycamore Lake by R. W. Dawson of Sycamore Flats, though no sycamore trees grow there; the name came from his property. Judge Benjamin Eaton's 1887 remark that the water was "clear as crystal" gave the lake its present name.

The campground sits about 1 mile (1.6 km) upslope from the lake, reached by a one-way paved road or a gentle forest foot trail. Camping costs $12 for the first car and $5 for a second, paid by fee envelope. The visitor center and cafe are open dawn to dusk except Tuesdays.

The natural lake, fed by snow and springs, varies in depth due to a fissure in its granite bed affecting water levels throughout the year. This geological feature creates noticeable changes in how the lake appears and fills depending on the season.