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).


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.


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 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
  • Green Trails Mount Si NRCA No. 206S
  • Green Trails Mt Si No. 174
  • USGS Mt Si

Upcoming Activities

Day Hike - Mount Si Main Trail

Day Hiking Trip
Join us for hot cocoa and bring/ring in the 2022 new year by being among
Difficulty: Moderate/Strenuous
Sat, Jan 1, 2022
No Prerequisites
1 participant 0 leaders
Registration opens Dec 1
Seattle Branch

Field Trip - Baseline Conditioner - Mount Si Main Trail

Climbing Field trip: Basic Alpine Climbing Course
The Baseline Conditioner for the course
Difficulty: Moderate/Strenuous
Sat, Jan 22, 2022
No Prerequisites
12 participants 11 instructors
Registration opens Nov 1; Instructor registration open now
Foothills Branch
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.

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

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