Mount St. Helens · Worm Flows
Worm Flows from Marble Mountain Sno-Park
The Route
The Worm Flows route climbs from Marble Mountain through the Swift Creek corridor and volcanic ridges to the south crater rim.
- Marble Mountain Sno-ParkSwift Ski Trail #244 starts the approach.
- Chocolate FallsThe route reaches the Swift Creek area around 3,700 ft.
- TimberlineWooden posts mark the lower open route to about 4,800 ft.
- Worm Flows RidgeOpen ridges and slopes lead toward the upper mountain.
- Crater RimDescent returns to Marble Mountain on the same route.
Swift Ski Trail Approach
The approach begins at Marble Mountain Sno-Park, around 2,800 ft, using Swift Ski Trail #244. It climbs through forest toward Swift Creek; Chocolate Falls is a seasonal waterfall landmark near the transition into open volcanic terrain.
Creek Crossing & Lower Ridge
The Forest Service's route crosses to Swift Creek's west side above Chocolate Falls, around 3,700 ft. Wooden posts mark the lower open route as far as about 4,800 ft, above which the itinerary continues on ridges and open slopes.
Upper Mountain
MSHI identifies a seismic station around 6,200 ft below the upper snowfield. The route follows a jumbled lava-flow ridge toward the crater rim; the amount and continuity of snow vary rather than following a fixed elevation boundary.
Rim & Return
The rim is not the crater floor. The published return reverses the Worm Flows approach to Marble Mountain. MSHI says the route can be used year-round, despite its common winter-route name.
Published reference figures for the named itinerary. Source dates and access notices are separate from current terrain observations. Reference Set: 2026-10-23.
Weather
Current forecasts open at the providers below. NWS forecasts describe a terrain grid cell, not an exact summit.
Access
Marble Mountain Sno-Park, Washington · Mount St. Helens
Trailhead
Marble Mountain Sno-Park is on Forest Road 83, reached from Forest Road 90 east of Cougar.
Parking Permit
A Washington Sno-Park permit is required December 1–March 31 and is not sold at the trailhead.
Climbing Permit
The separate Mount St. Helens climbing permit applies above 4,800 ft; current quota dates are on Recreation.gov.
Facilities
The Sno-Park has vault toilets but no potable water. Winter parking follows the posted layout to preserve snow-removal access.
Permit Release & Group Size
Quota-season permits are released at 7 AM Pacific on the first day of the preceding month. Groups are limited to 12.
Permit Identification & Overnight Dates
Each listed climber must carry identification and a permit copy. Overnight travel within the climbing closure area requires permits for consecutive days.
Source information checked 2026-10-23. Road snapshots are dated separately.
Reports
MSHI Current Conditions
Open the publisher’s route-specific material and check its date and scope.
Forest Service Worm Flows Route
Open the publisher’s route-specific material and check its date and scope.
Links open the publishers’ report pages. Reports are not automatically imported or filtered to a forecast date.