Ontario Peak is a 8696 ft high peak in the San Gabriel Mountains of California. Like its neighbor Cucamonga Peak, it is in the San Bernardino National Forest, and in the Cucamonga Wilderness. The peak is named for the nearby city of Ontario, about 12 mi due south, and first appeared in the United States General Land Office Forest Atlas in 1908. The most accessible trailhead for hiking Ontario Peak is in Icehouse Canyon. Forest Service Trail 7W07 leads from here to Icehouse Saddle, from which the Ontario Peak Trail leads to the summit. This route is 13 mi round trip, with 4100 ft of elevation gain.