Sandy Glacier Caves, Mount Hood Wilderness

The Sandy Glacier Caves are a system of glacier caves within the ice of Sandy Glacier on Mount Hood, Oregon. They are thought to be the largest glacier caves in the lower 48 states of the United States. Surveys done in 2011 and 2012 have measured the system at over 1 mile in length or about 7,000 feet. The caves formed from internal glacial melting at what are the headwaters of the Muddy Fork river. As melting continues, the caves grow larger with their entrances melting their way up the glacier's slope. Eventually it is predicted the caves will be completely gone within 7 to 10 years once the interior melting has reached the surface of the glacier. ()