Start at the Climbers' Bivouac trailhead (elevation 3700') and follow Ptarmigan Trail (216A) for 2.1 miles, where the route meets the junction of the Loowit Trail. The vault toilet aka "last chance bathroom" is closed permanently. As the route steepens, emerge soon from the trees and get your first glimpse of the next phase of the climb, the boulders (elevation 4800'). Save your energy- the majority of the elevation gain is in the last 3 miles to the summit rim. Wooden pole cairns usher climbers along the blocky boulders of Monitor Ridge for another 2500 ft of elevation gain. You will pass Monitor Peak (elevation 5994' to the east of the route). A GPS station will appear at 7000', revealing a snake of boulders up the ridge. The final stretch is affectionately called the "Vertical Beach" and is akin to hiking a sand dune to the summit rim.

The route crests the crater's crescent-shaped rim, on a clear day revealing dramatic views of the peaks of WA and OR. Head West along the rim to the true summit, a 1/4 mile away at 8,363 feet. Savor the horizon on a clear day and descend on the route you came, following the wooden pole markers back to the trailhead.

Start at the trailhead from Marble Mountain Sno-Park (elevation 2800'). About 2 miles in, leave the forest and pass views of Chocolate Falls (elevation 3700'), a 40-foot seasonal waterfall along Swift Creek, heading into a barren landscape of mudflows and rock, where wooden cairn poles guide climbers from timberline to approximately 4,800 ft elevation. Continue to snake up the jumbled lava flow ridge up to the seismic station. The seismic station (elevation 6,200') is below the snow field that leads up to the crater rim.

The route crests the crater's crescent-shaped rim, on a clear day revealing dramatic views of the peaks of WA and OR. Head West along the rim to the true summit, a 1/4 mile away at 8,363 feet. Savor more sweet views before turning around for the return trip, hugging Worm Flow Ridge and retracing your route, back to the trailhead.