Mount St. Helens

Mount St. Helens ranks No. 78 among the Lower 48 Top 100 prominence peaks in the Prominence Registry, rising 8,330 feet in the Cascade Range of southern Washington, with 4,595 feet of clean prominence. It is the centerpiece of Mount St. Helens National Volcanic Monument in Skamania County. Most climbers use Monitor Ridge from Climber's Bivouac for 10 miles round-trip with 4,500 feet of gain on Class 2 terrain; climbing permits are required above 4,800 feet.

Mount St. Helens is the central feature of the 110,000-acre national volcanic monument, located about 52 miles northeast of Portland. USGS describes the volcano's eruptive history as beginning about 275,000 years ago, with the bulk of the modern edifice built during the last 3,000 years, making it among the youngest and most active stratovolcanoes in the Cascade Range. Before May 18, 1980, the peak stood 9,677 feet and held more than 5,000 feet of topographic prominence, placing it among the ultra-prominent peaks of the contiguous United States.

The 1980 eruption removed that ultra-prominent status along with roughly 1,300 feet of summit. A magnitude 5.1 earthquake triggered a massive debris avalanche from the volcano's north flank; the sudden unloading produced the lateral blast that devastated 230 square miles to the north, killed 57 people, and left a horseshoe-shaped crater approximately one mile wide and two miles long, open to the north. Inside the crater, Crater Glacier wraps around the post-1980 lava dome complex. USGS rates Mount St. Helens as Very High threat potential and identifies it as one of the most likely volcanoes in the contiguous United States to erupt again.

Monitor Ridge

The standard summer route departs from Climber's Bivouac at 3,700 feet on the south flank, covering 10 miles round-trip and gaining 4,500 feet to the crater rim. Ptarmigan Trail #216A climbs 1,100 feet through second-growth forest over 2.25 miles to the Loowit Trail junction at 4,800 feet, where the permit threshold begins.

Above treeline the route follows Monitor Ridge on large lava boulders with no established switchbacks, navigating between periodic wooden marker posts to roughly 7,000 feet; most parties identify this boulder section as the most time-consuming terrain of the ascent. The posts end at monitoring equipment near 7,000 feet, and the final 1,300 feet is unmarked loose pumice and ash where the shifting surface makes every upward step work harder. Most parties complete the round-trip in 7 to 12 hours. The Worm Flows route from Marble Mountain Sno-Park serves as the winter alternative, covering 12 miles with 5,500 feet of gain and typically requiring crampons, ice axe, and avalanche awareness.

Key Landmarks

• Loowit Trail junction / timberline (4,800 ft) — permit required above this point
• End of marker posts / monitoring station (~7,000 ft)
• Vertical Beach (7,000–8,330 ft)
• Crater rim (8,330 ft LiDAR) — registry high point lies approximately 300 yards west along the rim

No ropes or technical gear are required on the standard summer Monitor Ridge route, but navigation skills are essential above 7,000 feet where marker posts end; carry map, compass, and GPS. Crampons, ice axe self-arrest, and avalanche awareness are required on the Worm Flows winter route. Crater rim cornice collapses without warning through much of the season and have caused fatal falls. Ongoing rockfall from actively eroding crater walls is most frequent during spring thaw. No reliable water above the trailhead makes heat and dehydration significant risks on summer ascents. Volcanic activity cannot be predicted with certainty; check USGS Cascades Volcano Observatory and USFS alerts before climbing, as access may change during periods of unrest.