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Mount St. Helens - Worm Flows Route

South Cascades


South Cascades -- Mount St. Helens
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12.0 miles, roundtrip


Gain: 5699 ft.
Highest Point: 8364 ft.


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The Worm Flows Climbing Route, from Marble Mountain Snow-Park, is the most direct route to the summit of Mount St. Helens during the winter season. Ice axe, crampons, and avalanche awareness are recommended on this route. Skis with climbing skins or snowshoes with cleats are also highly recommended. Looking for the summer route? Find it here. 

Named for the rivers of rocky lava that surround the trail, the 10.8-mile Worm Flows route ascends nearly 5,700 feet to the summit of Mount St. Helens. Although challenging, this standard winter and spring route provides a non-technical climb for experienced hikers craving sweet summit views and a chance to practice basic mountaineering skills.

Start at the Marble Mountain Sno Park. Cross to the west side of Swift Creek, just above Chocolate Falls, at an elevation of 3,700 feet. Follow ridges and open slopes to the crater rim. Wooden route marking posts guide climbers from timberline to approximately 4,800 feet of elevation. About two miles in, leave the forest and pass views of Chocolate Falls, a 40-foot waterfall along Swift Creek, heading into a barren landscape of mudflows and rock, where large posts and occasional cairns mark the way. Navigate through the jumbled lava flows, then push beyond cloud level toward St. Helens' false summit.

The route crests the crater's crescent-shaped rim, revealing dramatic views of Spirit Lake and Mount Rainier. But you're not finished yet. Head west along the rim to the true summit, a mound of rocks at 8,365 feet. Savor more sweet views before turning around for the return trip back to the trailhead.

Hike safely - to reduce your exposure to avalanche potential, stay away from snow loaded slopes and gully bottoms. Stay off the cornices at the crater rim.

WTA Pro Tip: Winter climbers can self-issue their permits at the Climber's Bivouac trailhead. No fee is required for permits between November 1 and March 31. If you'd like to summit St. Helens in the spring, summer, or fall, a paid permit is required. Learn more by visiting their website


Mount St. Helens - Worm Flows Route

Map & Directions

Co-ordinates: 46.1308, -122.1696 Open map in new window


South Cascades -- Mount St. Helens

Mount St. Helens National Volcanic Monument

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Guidebooks & Maps

USGS Mount St Helens

Buy the Green Trails Mt St Helens No. 364S map

Getting There

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


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Mount St. Helens - Worm Flows Route

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