Grimface Mountain is a 2,635-metre summit in southern British Columbia within Cathedral Provincial Park and Protected Area, about 3 kilometres north of the Canada–United States border. It is the park’s highest point, the highest in the Similkameen Division Yale Land District, and the fourth-highest peak in the Okanogan Range. Its steep rise above Wall Creek gives it striking local relief, while its slopes drain to tributaries of the Ashnola River. Officially named in 1979, the mountain stands in a North Cascades landscape shaped by tectonic uplift, faulting, volcanic processes, and Pleistocene glaciation, with a Cascade climate marked by snowy winters and clearer summers.