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.
From Cougar, WA drive east on Lewis River Road, which turns into Forest Road 90. Continue on Forest Road 90 until the intersection with Forest Road 83. Turn left on Forest Road 83 and continue approximately 6 miles to the Marble Mountain Sno-Park. During the winter and early spring Forest Road 83 is gated at the Sno-Park.