Marble Mountain Sno-Park is the starting point for the Worm Flows Climbing Route for Mount St Helens Summit. This is the primary climbing route used during the winter. Marble Mountain Sno-Park offers a trail system that includes 25 miles (snowmobile), and 78.4 kilometers ungroomed (ski). This area is shared with motorized and non-motorized recreationists.
The Sno-Park is a large parking lot that is the main gateway to many winter activities in the area including: snowmobiling trails, snowshoeing, cross-county skiing, and the beginning of the winter hike to the summit of Mount Saint Helens: the Worm Flows Route. A Sno-Park permit is required to park during the winter season and climbers to the summit must register before beginning the hike.