Mount Si Main Trail

A moderate/strenuous 8-mile round trip day hike with 3,200 feet of elevation gain. This is a popular trail in the foothills that offers a good workout and views of Puget Sound and the Upper Snoqualmie Valley. Variations include the Talus Loop, "Double Si" or "Si, Si Again" conditioner, Blowdown Mountain, Crater Lake Mountain, and Dixie Peak.

Getting there

Take Exit 32 off of I-90 and turn left (north) onto 436th Ave SE. Drive 0.5 mile  and turn left (west) onto North Bend Way nd in 0.25 mile, turn right (north) onto Mount Si Road. Continue 2.5 miles and turn left into the large trailhead parking lot (660 ft).

PUBLIC TRANSPORTATION - TRAILHEAD DIRECT

On weekends and designated holidays, Trailhead Direct takes riders to three hiking destinations: Mount Si, Issaquah Alps, and Mailbox Peak. All buses are run by King County and regular fares apply, just like in the city. By establishing this service, Trailhead Direct aims to increase accessibility to local trails, limit vehicle congestion in trailhead parking lots, and reduce carbon emissions. If you will have a group of more than 10 people, please fill out this form to reserve seating.

on the trail

Mount Si (3,900 ft)

8 miles round trip, 3,159 feet of elevation gain, Difficulty: Moderate/Strenuous

The Mount Si "main" Trail begins at the far corner of the parking lot where just past the picnic area and outhouse. The trail is moderate for the first two miles and then steepens with more switchbacks until it ends in the meadow at the top.

The Talus Loop Trail makes an excursion off the main Mount Si Trail, reconnecting at Snag Flats.  It's 1.3 mi instead of the 1.0 mi if you were to stay on the Mount Si Main Trail.

"Si, Si Again" or "Double Si" Conditioner: Hike up the Mount Si Main Trail to the viewpoint near the summit, down the main trail, lunch in the parking lot, then a car shuttle to the Little Si Trail parking lot, up the Boulder Gardens/Old Si Trail to the viewpoint, down the  trail, car shuttle back to Little Si. Great for conditioning!  It's 16 miles and 6,400 feet of elevation gain.

Note: The "haystack" jutting out of the meadow is the true summit and is a challenging and exposed scramble route. It is not appropriate for day hikers.

scramble routes

Mount Si HaySTACK (4,180 FT)

8 MILEs ROUND TRIP SCRAMBLE, 3,360 FEET OF ELEVATION GAIN, DIFFICULTY: STRENUOUS 3, TECHNICAL 4

From the meadow at the top of Mount Si continue northeast on the path to a wooden bench that marks the start of the Haystack scramble route. The path continues north to a rocky northeast-facing gully. Holds are plentiful and the rock is generally sound. There are many paths up the gully until you reach the saddle between the main and north summits. From here, turn south (climber's left) and make a few slabby exposed moves to reach the summit.

blowdown mountain (4,560 ft) and crater lake mountain (4,351 ft)

12 miles round trip scramble, 4,400 feet of elevation gain, difficulty: strenuous 4, technical 2

From top of Mount Si continue on the path and road to where that road terminates northwest of Mount Teneriffe. Ascend past 4,440 ft, then follow the ridge northwest, descend west to a saddle, and then ascend continuing west to the summit of Blowdown Mountain. The views are not great, but in winter, this is all that daylight may allow. From Blowdown Mountain, travel north, descending to a saddle and then ascending to Crater Lake Mountain.

Dixie Peak (4,606 ft)

4,400 feet of elevation gain, difficulty: strenuous 4, technical 4

From top of Mount Si continue on the path and road to where that road terminates northwest of Mount Teneriffe. Ascend past 4,440 ft, then follow the ridge northwest and then north to Dixie Peak.

INFORMATION FOR LEADERS

scheduling & permits

  • Permits are required in this area for all fee-based (course-related) activities, regardless of group size.  Leaders may list trips at this route/place with the understanding that they need to verify that a permit has been obtained before running the trip (if required as outlined above). Permit applications are submitted to WA Department of Natural Resources annually in December. Please contact info@mountaineers.org with any additional questions. More details about permitting on WA DNR land as it applies to Mountaineers trips, as well as our current year Land Use License, can be found on our Washington State Department of Natural Resources (DNR) page.
  • This route allows multiple bookings. Please check scheduled trips listed below in the "Activities" tab to see if there is another group already booked on the same day. Leaders are expected to contact the leader(s) of existing trips to ensure there are no concerns or conflicts, according to The Mountaineers Outdoor Ethics Policy. Please review our Group Size & Multiple Bookings page for guidance.
  • Scrambles of Mount Si Haystack, Blowdown Mountain, Crater Lake Mountain, and Dixie Peak may also be scrambled from the Mountain Si Old Trail. Please be sure to review activities on the Mount Si Old Trail route/place and contact the leader(s) of existing trips to the same destination to ensure there are no concerns or conflicts, according to The Mountaineers Outdoor Ethics Policy. Please review our Group Size & Multiple Bookings page for guidance.
  • Difficulty: Moderate/Strenuous
  • Length: 8.0 mi
  • Elevation Gain: 3,150 ft
  • 3,900 ft
  • Land Manager: Mount Si NRCA
  • Parking Permit Required: Discover Pass
  • Recommended Party Size: 12
  • Maximum Party Size: 65
  • Maximum Route/Place Capacity: 65
Map
  • Green Trails Mount Si NRCA No. 206S
  • Green Trails Mt Si No. 174
  • USGS Mt Si
Activities

Upcoming Activities

TAC MAC Conditioner Series - Mount Si Main Trail

Youth & Day Hiking Field trip: Mountaineers Adventure Club - Tacoma
Training hikes and scrambles to get us into shape!
Difficulty: Moderate/Strenuous
Wed, Nov 9, 2022
No Prerequisites
10 participants 1 instructor
Registration opens Oct 1; Instructor registration open now
Tacoma Branch

Climbing Conditioner - Mount Si

Climbing Clinic: Basic Alpine Climbing Course
Conditioning hikes, snowshoes, scrambles, and anything else related to fitness for climbers and climbing students.
Difficulty: Strenuous
Sat, Apr 1, 2023
No Prerequisites
6 participants 1 instructor
Registration closes Mar 30
Olympia Branch
Trip Reports
Titles

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.

  • Mount Si
  • Mount Si via Talus Loop
  • Talus Loop
  • Si, Si Again
  • Double Si
  • Mount Si Haystack
  • Blowdown Mountain
  • Crater Lake Mountain
  • Crater Lake & Blowdown Mountains
  • Dixie Peak
Resources

There are no resources for this route/place. Log in and send us updates, images, or resources.