Sahale Peak/Quien Sabe Glacier

Boston Basin and Cascade Pass area is renown for its alpine environment. Climb Sahale Peak, Sharkfin Tower, and/or Boston Peak for an excellent alpine experience on glacier and Class 4 to low Class 5 rock climbing depending on the route.

getting there

Drive I-5 to just north of Mount Vernon, then east on SR-20 (North Cascades Highway) to Marblemount. Sign in at Ranger Station and get a permit. Continue east on Cascade River Road about 21.7 miles to the old Diamond Mine Road (fork in road about 1.5 miles from the end of Cascade River Road, 3,220 ft). There is limited parking at the fork.


From the fork, walk about 1 mile on the old mine road to where the trail leaves the road sharply right and steeply up. Follow this steep, well worn trail to Boston Basin. Camp in Boston Basin (6,200 ft).


sahale peak/quien sabe glacier (8,680 ft)

basic glacier climb

 There are two ascent routes. The easier route follows the left side of the Quien Sabe Glacier to the top of the left side then traverses right along the base of the rock face below Sharkfin Tower. Continue traversing until the Glacier begins to steepen toward the Col. The alternate ascent is significantly shorter and much more direct. Scramble from camp to the right side of the Glacier. Work through the crevasses of the lower section of the glacier (up to 45° and very exposed). The two ascent routes merge about half way up the Quien Sabe Glacier to the Boston-Sahale Col. From the col traverse right to the summit. Take ice ax and crampons for short but exposed snow traverse on Col to summit block. Scramble loose rock to summit (Class 3).

  • The direct route is a lot shorter on the ascent but is only for experienced climbers who do not mind some exposure.
  • This climb can be done as one long day (12-14 hours) but best done as two days to avoid a late return.
  • This is an excellent late season climb.

sharkfin tower/Southeast ridge (8,120 ft)

Basic Rock Climb

From camp, ascend snowfields on left side of Quien Sabe Glacier to near upper left corner of glacier just below Sharkfin Col. Rope up and traverse east along top of glacier for several hundred feet to couloir below peak (35° snow early season, class 2-3 gully in late season). If berschrund or serac problems at base of couloir, climb slabs (Class 3-4) on left and intersect couloir 100 ft up. Ascend snow field to notch east of peak.  (Look for rappel anchors to be used later on the descent). The first pitch (Class 4 to low Class 5) goes onto north face, then up to obvious notch at base of steep south facing ridge. The second pitch (Class 4) stays a few feet left of ridge; go 30 ft past obvious rappel anchor to where ridge turns west and lays back. Third pitch ascends exposed class 4 rock to summit (8,120 ft).

  • Rock is generally sound.
  • This climb can be done in one long day with car camp the night before.
  • Any leader considering this climb make sure that the students are strong, confident and capable. Although the route is rated 5.0, there are a couple of 5.4 moves.

boston peak/Southeast Face (8,894 ft)

basic glacier and rock climb

From camp continue on climber's left towards the left side of Sharkfin Tower. Rope up at ~6,700 ft. Make a rising traverse near the cliffs below Sharkfin to a flat portion of the Quien Sabe glacier. Pick a line up the steeper portion of the glacier avoiding crevasses. Later season, it is usually best to traverse to climber's right to end run the bergschrund, then cut up and left above the bergschrund up to the Boston-Sahale col. Unrope at the col, coiling ropes.

Follow the ridge towards Boston Peak. The ridge is initially flat, then widens onto loose rock. Stay on the right, generally following right on the crest. The ridge steepens, widens, then narrows to a knife edge (exposed Class 3-4). At the high point of the ridge you will see the false summit ahead of you. Make some class 4 moves down and follow a trail along the edge of the cliff to the right (east) which leads around the false summit. You may find cairns marking this route. After about 100 feet you'll suddenly come into sight of the Boston Glacier and the summit pyramid of Boston Peak.

Cross the glacier above the bergschrund (about 200 feet), and attain a small ledge on the left just before the summit block. There may be a moat here, but usually it is manageable. Note rappel slings above you on the South Face of Boston. Climb up a few feet to a wide, downsloping ledge covered in loose stones, and follow it around the east side of Boston for about 100-200 ft to its end.

Build an anchor here and rope up for the first technical rock pitch. Follow the rock up, trending to climber's right on a series of ledges covered in small rocks and sand. After about a half a rope length, the easiest line starts to trend left. Setup a belay here. Lead up and left less than a half rope length, up a wide chimney and encounter the crux: either a wide offwidth crack straight ahead or a rib to the right. Climb one of these features to attain the ridge, and set up a belay. The third pitch is just an exposed scramble (Class 3-4). Belay from here to the summit placing one or two pieces.

  • This is a serious climb. It is best suited for strong students and experienced leaders. The climb is more reasonable as a two day trip, but can be done as a very long day with a car camp. Consider limiting the party size to four.


sahale peak

Descend via the easier climbing route.

sharkfin tower

Descend by rappelling and downclimbing the route (about five rappels).  This allows you to return to where you have stashed any glacier travel gear, etc. Alternatively, descend the west face. Just below the summit, on the west side, should be a rappel anchor. One double rope rappel gains the west col.cNote that there are usually established rappel anchors on the rock walls along the steep couloir that one can use to descend to the Quien Sabe Glacier.  Look for these on the way up the couloir.

boston peak

Rappel the South Face with either three 50 m rappels or a short rappel and a 60 m rappel.


sahale peak

Trailhead to Camp 2-3 3,180
Camp to Summit 4-6 2,600
Summit to Camp 2-3
Camp to Trailhead 2

sharkfin tower

Trailhead to Camp 2-4 3,180
Camp to Summit 6-8 1,900
Summit to Camp 2-3
Camp to Trailhead 2-3

boston peak

Trailhead to Camp 2-3 3,200 ~4
Camp to Summit 7-9 2,500 ~1.5
Summit to Trailhead 4-5 ~5.5


sahale peak

Standard glacier gear-fluke or picket in early season, screws in late season. A small rock rack for the summit may be useful.

sharkfin tower & Boston Peak

Standard glacier gear-fluke or picket in early season, screws in late season, and a standard alpine rock rack.

  • Suitable Activities: Climbing
  • Climbing Category: Basic Alpine
  • Seasons: July, August, September
  • Weather: View weather forecast
  • Difficulty: Basic Glacier Climb, Basic Rock Climb, Strenuous 3, Technical 2
  • Elevation Gain: 5,780 ft
  • 8,680 ft
  • Land Manager: North Cascades National Park
    Stephen Mather Wilderness
  • Parking Permit Required: None
  • Recommended Party Size: 12
  • Maximum Party Size: 12
  • Maximum Route/Place Capacity: 12
  • Green Trails Cascade Pass No. 80
  • USGS Cascade Pass
Trip Reports

This is a list of titles that represent the variations of trips you can take at this route/place. This includes side trips, extensions and peak combinations. Not seeing a title that fits your trip? Log in and send us updates, images, or resources.

  • Sharkfin Tower/Southeast Ridge
  • Sahale Peak & Sharkfin Tower
  • Sahale Peak/Quien Sabe Glacier & Sharkfin Tower/Southeast Ridge
  • Boston Peak/Southeast Face
  • Boston Peak/Southeast Face via Quien Sabe Glacier
  • Boston & Sahale Peaks
  • Boston Peak & Sahale Peak
  • Boston Peak, Sahale Peak & Sharkfin Tower

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