Lots of rocks, roots, and loose gravel. This is a popular trail with plenty of visitors on it, so watch out when coming down and make sure to yield and signal when passing. Some visitors let their dogs off leash here and they can get startled easily.
There are 2 parking lots in close proximity to each other, one right after you cross the Mount Si bridge and one just a little beyond that. They are connected by a little gravel path about 100 yards long.
The trailhead is well signed and easy to follow for the first mile. Then it gets a bit confusing because the rocks break up any semblance of a trail. Watch where people go or you may end up going slightly off trail. For the most part, it is easy to follow the trail as there is always someone in front of you, especially on the weekend when it can get really busy. I would recommend coming in the early morning or on a weekday to get parking. I came on a Monday and still had to park in the overflow lot.
It's pretty much a straight shot all the way to the top, with no clear areas for breaks. Once at the top the view is gorgeous - similar to Mt. Si
but a lot less work! You can see the haystack on Mt. Si
from the top of Little Si.
Regular PNW old growth forest. Some song birds at the top along with chipmunks that are used to humans feeding them (but please don't!).