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Observation Peak via Big Hollow Hike

From Oregon Hikers Field Guide

Old-growth Douglas-fir grove, Big Hollow Trail (bobcat)
The log crossing, Big Hollow Creek (bobcat)
Bunchberry, brambles, and lichen, Big Hollow Trail (bobcat)
Looking to Mt. Hood from Observation Peak (bobcat)
Explorer's gentian (Gentiana calycosa), Observation Peak (bobcat)
The route to Observation Peak via the Big Hollow Trail; the Sister Rocks extension also shown (not a GPS track) (bobcat) Courtesy: Caltopo
  • Start point: Big Hollow TrailheadRoad.JPG
  • End point: Observation Peak
  • Trail Log:
  • Hike Type: In and out
  • Distance: 10.4 miles
  • Elevation gain: 2755 feet
  • High Point: 4,207 feet
  • Difficulty: Moderate
  • Seasons: Late spring into fall
  • Family Friendly: No
  • Backpackable: Yes
  • Crowded: No


Hike Description

The Big Hollow Trail rises gradually along the northern slope of Howe Ridge and enters the Trapper Creek Wilderness north of Observation Peak. It offers few views but passes through some towering groves of old-growth Douglas-fir and western hemlock. This trail offers more exertion than the Observation Peak Hike to the two summit areas of the wilderness: Sister Rocks and Observation Peak, both of which can be attained on a moderate day’s outing. The description below details the route to Observation Peak and an add-on to Sister Rocks; see the Sister Rocks Hike for a description of the short hike to that destination.

Fill out your wilderness permit at the trailhead and wind through a leafy bottomland of Douglas-fir and mossy big-leaf maples. Soon, you’ll reach Big Hollow Creek. A notched log offers slippery passage when the creek is high, but otherwise it may be possible to cross using stepping stones. Reach a grove of maples and the Big Hollow-Dry Creek Trail Junction.

Proceed up the slope from here, quickly entering old growth Douglas-fir/ western hemlock forest with a carpet of Oregon grape and salal. Traverse upward with a shallow gully on your left, and then continue ascending among stands of large Douglas-firs. Shortly, you’ll begin a long traverse that heads gradually up a slope that sees some windfall. Note the many yew trees in the understory here. At a break in the trees, get a view across the creek valley to Paradise Ridge. After hiking along a hillside of much younger trees, dip into a moss-carpeted depression and then continue upward. Pass under a mossy rock face, and hear the rushing South Fork of Big Hollow Creek below. The trail levels as it negotiates a patch of huckleberry, and then crosses the South Fork with its beautiful moss-lined pools.

Past the creek, look for a couple of insulator coils on a tree. These once carried the telephone wire to the Observation Peak Lookout. Traverse up a slope, and hike below a couple of talus fields with their own alarm-calling pika populations. Next is an extensive thicket of salmonberry and Sitka alder which gushes with several small streams. Now in silver fir/noble fir forest, you'll encounter a wilderness sign; then, keep right at a fork to reach Berry Camp at the junction of the Observation and Big Hollow Trails.

Turn left, and keep along the ridge for another 50 yards before you come to the four-way Observation-Trapper Creek Trail Junction (A shortcut from the Big Hollow Trail comes in from the left). Keep straight and traverse a slope to reach the Observation-Shortcut Trail Junction on a saddle, and then, 25 yards later, the Observation-Observation Peak Trail Junction.

Go right on the Observation Peak Trail #132A, which traverses up through bear-grass and huckleberry bushes. Soon a spur leads left to a rocky ridge, which you can ascend to get views of Mount Adams, Mount Rainier, and Mount Saint Helens as well as down the spine of Howe Ridge and over the Wind River valley. The trail keeps just below the ridge crest, passing more viewpoints. Hike up through the bear-grass to Observation Peak’s summit, site of a former lookout cabin, where the expansive views include Mount Hood as well as the three closest Washington stratovolcanoes. After taking in the vista and the wildflower bloom (best here in early summer), return the way you came.

Add-on hike to Sister Rocks:

  • Additional distance: 1.8 miles round-trip from Berry Camp
  • Additional elevation gain: 435 feet
  • High point: 4,268 feet

From Berry Camp, continue straight (north) up through bear-grass and huckleberries on the Observation Trail #132. The trail levels and then ascends gently to the ridge crest and the Observation-Sister Rocks Trail Junction (A sign for Sister Rocks is just down that trail on a tree). A little beyond the junction is rocky viewpoint, which is worth a stop as it provides a good vista towards Mount Adams, Mount Saint Helens, and Mount Rainier. Take the Sister Rocks Trail up through noble/silver for forest, drop a little, and then hike steadily up to a rock viewpoint carpeted with lichen, moss, and common juniper. Some of the view here is blocked by trees, so continue on to descend and then hike up steeply to the crest of the first Sister Rock, distinguished by its rusting pipe.

Just to the west is Second Sister, a short scramble down and up, which offers more expansive views than First Sister. Looking south, you’ll see the Trapper Creek drainage, with Howe Ridge and Observation Peak on the left and Soda Peaks on the right. Mount Hood dominates the far horizon. To the west, get a view across the Siouxon Creek drainage to Siouxon Peak and Huffman Peak. Look north and east to Mount Saint Helens, Mount Rainier, and Mount Adams. Notice also that there are three Geodetic Survey markers, used for triangulation purposes, on Second Sister!

The Sister Rocks Research Natural Area, which includes the two rock outcroppings of Sister Rocks, was established for the study of climax silver fir forest.


  • Maps: Hike Finder
  • Green Trails Maps: Wind River, WA #397 and Lookout Mtn, WA #396
  • Trapper Creek Wilderness (USFS)
  • U.S. Department of Agriculture, Forest Service: Mt. Adams Wilderness, Indian Heaven Wilderness, Trapper Creek Wilderness
  • U.S. Department of Agriculture, Forest Service: Mt. Adams Ranger District
  • U.S. Department of Agriculture, Forest Service: Gifford Pinchot National Forest
  • National Geographic Trails Illustrated Map: Mount St. Helens - Mt. Adams

Regulations or Restrictions, etc.

Trip Reports

Related Discussions / Q&A

Guidebooks that cover this hike

  • Hiking Washington’s Mount Adams Country by Fred Barstad
  • Day Hiking: Columbia River Gorge by Craig Romano
  • 33 Hiking Trails: Southern Washington Cascades by Don & Roberta Lowe

More Links


Oregon Hikers Field Guide is built as a collaborative effort by its user community. While we make every effort to fact-check, information found here should be considered anecdotal. You should cross-check against other references before planning a hike. Trail routing and conditions are subject to change. Please contact us if you notice errors on this page.

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