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.

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 (600 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)

A moderately strenuous 8-mile round trip hike with 3,159 feet of elevation gain

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 "haystack" jutting out of the meadow is the true summit and it can be scrambled. The route is challenging and exposed, and it' easy to send rock fall to unsuspecting hikers below, so this is not recommended.

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.

scramble routes

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

a 12-mile round trip scramble with 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)

a scramble with 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, and all free activities involving 13 or more people. 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 here.
  • 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.
  • 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

Conditioning Hike - Mount Si Main Trail

Day Hiking Field trip: Compressed Alpine Scrambling Course
Scramble conditioning hike for K-POD
Difficulty: Moderate/Strenuous
Sun, Apr 18, 2021
No Prerequisites
1 participant 0 instructors
Registration closed Feb 11
Seattle Branch

Day Hike - Mount Si Main Trail

Day Hiking Trip
Afternoon hike/workout. Open to all members, need to be able to get to the summit
Difficulty: Moderate/Strenuous
Mon, Apr 19, 2021
No Prerequisites, Leader's Permission Required
0 participants 0 leaders
Registration opens Apr 16
Tacoma Branch

CHS 2 Hike - Mount Si Main Trail

Day Hiking Field trip: Conditioning Hiking Series
A popular trail in the foothills that offers a good workout and views of Puget
Difficulty: Moderate/Strenuous
Sat, May 15, 2021
No Prerequisites
5 participants
Registration opens Apr 21
Seattle Branch

Conditioning Hike - Mount Si Main Trail

Day Hiking Field trip: Hiking Conditioning Series
Scheduled day hike with pack at 30% bodyweight
Difficulty: Moderate/Strenuous
Sat, May 22, 2021
No Prerequisites, Leader's Permission Required
2 participants
Registration closes May 20
Bellingham Branch

CHS Tacoma May Hikes - Talus Loop

Day Hiking Field trip: Conditioning Hiking Series
Trip will initially open to Tacoma Branch Conditioning Hiking Students. Trip will open for registration
Difficulty: Moderate/Strenuous
Sat, May 29, 2021
No Prerequisites
2 participants
Registration closes May 27
Tacoma Branch

Conditioner Hikes - Mount Si Main Trail

Day Hiking Field trip: Intensive Basic Alpine Climbing Course
Last chance to get a timed conditioner in before the course.
Difficulty: Moderate/Strenuous
Thu, Jun 3, 2021
No Prerequisites
4 participants 0 instructors
Registration closes Jun 1
Seattle 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 via Talus Loop
  • Talus Loop
  • Si, Si Again
  • Double Si
  • 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.