Cowles Mountain rises to 1,593 feet above sea level, making it the highest point within the city limits of San Diego — not the highest in the county, not the highest in the region, but definitively the highest within the city's boundaries, a distinction that draws several hundred thousand visitors to its summit each year. The mountain sits at the heart of Mission Trails Regional Park, the 7,220-acre preserve that surrounds it on all sides. The geology underfoot is old: Jurassic and early Cretaceous metavolcanic rock, formed when this part of California was something else entirely. The name honors George A. Cowles, a rancher who worked the surrounding land in the 1870s and 1880s.

San Diego State College students climbed the mountain in 1931 and painted a letter S — 400 feet of whitewashed rock — on the south-facing slope. It was the kind of thing college students did in that era, claiming a mountain as institutional territory, and it worked: the S was visible from large portions of the eastern city, and the mountain became S Mountain in the local vocabulary. For eleven years the student body maintained it, repainting as needed, keeping the claim fresh. The Army's order to cover it in April 1942 was practical rather than hostile — any landmark conspicuous from the air was a potential navigation aid for enemy aircraft — but it effectively ended the tradition. The mountain has been called Cowles Mountain ever since, and the S has never returned.

The standard route to the summit follows the main trail from the Big Rock trailhead on Golfcrest Drive: 1.5 miles, 950 feet of elevation gain, switchbacks through chaparral on sun-exposed southern slopes. It is not a technically demanding hike, but the combination of altitude gain, southern exposure, and San Diego's characteristic warmth means it demands more than it looks on paper. The trail is wide and well-maintained, heavily trafficked on weekends, and reliably busy at sunrise when regulars time the climb to catch the light over the eastern valleys. From the summit, on clear days, the Pacific is visible to the west and the Anza-Borrego desert to the east — the full width of San Diego County, from ocean to desert, in a single view.

Cowles Mountain exists within Mission Trails Regional Park, and the park gives it context. The San Diego River flows through the park below the mountain; the Old Mission Dam, built in 1803 by mission labor to irrigate the fields of Mission San Diego de Alcalá, sits inside park boundaries. The park itself was established in 1974 and has grown to become the sixth-largest municipally owned park in the United States. In 2024 it celebrated the fiftieth anniversary of acquiring Cowles Mountain, though the mountain's role as the city's highest point predates any park designation by geological time. Twenty-three bat species have been recorded in the park. The summit itself is marked by a benchmark and a modest cairn, nothing more — the view being monument enough.