Cowles Mountain, Mountain summit in San Carlos, San Diego, California, United States

Cowles Mountain is a 486-meter summit in San Diego's San Carlos neighborhood, the city's highest point, within Mission Trails Regional Park. Its main trail starts at Golfcrest Drive and Navajo Road, climbing 1.5 miles with about 290 meters of elevation gain to a flat top with two antenna masts. A second trail begins near Boulder Lake Avenue and Barker Way.

The mountain takes its name from George A. Cowles, a rancher and businessman who held influence in the San Diego region during the 1870s and 1880s. The name honors his role in shaping the area's development.

For decades, students from San Diego State University painted a large letter on the mountainside as a student tradition, until environmental protection rules stopped the practice. This symbol was a recognizable landmark and became part of the local community's sense of place.

The trail is well-marked with multiple routes to the summit, and the main entrance is at Golfcrest Drive. Wear sturdy shoes and bring water, as the path offers little shade during the climb.

The summit's rock is Jurassic and early Cretaceous metavolcanic and shallow intrusive igneous rock, resistant enough to erosion that it was never buried by later Cretaceous and Tertiary sediments. Small plateaus on the south and east slopes are remnants of the Poway Terrace, a near-sea-level erosional surface now about 370 meters up. A former seacliff on the west side rises above a dry wave-cut terrace at roughly 180 meters.