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blueBlack Mt. Si

  4.4 ( 104 ) Favorite


6.6 mile 10.7 kilometer out and back


Ascent: 3,281' 1,000 m
Descent: -3,282' -1,000 m
High: 3,999' 1,219 m
Low: 717' 219 m


Avg Grade: 19% (11°)
Max Grade: 41% (22°)


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A steep, well-maintained trail takes you atop Mt. Si with outrageous views of Puget Sound.

Benjamin Pontecorvo

Features Birding · Fall Colors · River/Creek · Views · Wildlife

Discovery Pass required year round.


This is a classic, well-traveled hike leading to the top of Mt. Si. There is a small portion of scrambling at the summit that is optional.

Need to Know

Go as early as you can. Google Maps may say that the trailhead opens at 6am, but I was there by 5:30am and running with no problems. I met people on the trail who had gone up for sunrise and said they'd started at 2:30am. So no worries about the trailhead not being open.

Expect the trailhead parking to be full by 9am.


From the trailhead, follow the well marked "Mt. Si Trailhead" or just follow the throngs of people on this deservedly popular trail. The endless switchbacks and steep terrain begin almost immediately, and will continue until the very top. This trail offers intermediate terrain that can be useful for both the novice hiker and a more experienced outdoors person training for a bigger objective. You'll gain more than 3000 vertical feet in under four miles of beautiful old growth forest. The canopy finally breaks close to the top, revealing some views to the South.

Once out of the forest, there are many outcroppings to enjoy your lunch and some views. Most people will stop here- but the more adventurous can continue uphill and right on a stony path to the Haystack, Mt. Si's true summit. This extra 150 ft of scrambling is class 3/4 and is well worth is as the views to the North are revealed.

On your way down please do not cut trails. What saves you 30 seconds can cause decades of damage. Also you'll need a discovery pass to park at the lot. Have fun!

Flora & Fauna

You will walk over three miles through old growth forest.

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Jul 15, 2019
200 up (inc 30 mins lost) 130 down — 3h 30m
Jul 14, 2019
John Barsanti
9.2mi — 4h 30m
Jul 4, 2019
Rachel Dier
Jul 4, 2019
Shawn Dier
Jun 29, 2019
Michael Reed
Jun 16, 2019
Claudia Ki
this is the old trail, there is another trail that ends up being 8miles 6.6mi
Jun 16, 2019
Kyle Harvey
Jun 16, 2019
Alexander Tolstoy

Trail Ratings

  4.4 from 104 votes


  4.4 from 104 votes
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