Big Four Ice Caves are seasonal ice caves at the base of Big Four Mountain in Washington’s Cascade Range, where the mountain’s steep north face creates deep shade that lets avalanche debris persist year-round. This accumulation of snow and ice forms an unusually low-elevation glacier-like mass, and in summer meltwater streams carve caves beneath it. Reached by the Big Four Ice Caves Trail in the Mount Baker-Snoqualmie National Forest, the area attracts more than 50,000 visitors annually. Despite its beauty and popularity, it is dangerous: cave-ins and slides have killed hikers, rangers warn visitors to stay out of the caves, and flooding and erosion have repeatedly disrupted access.