Goat Mountain Trail is a 17.7 mile out and back trail located near Mossyrock, WA that features a lake and is rated as moderate. The trail is primarily used for hiking, horses, and mountain biking and is accessible from May until November. Horses are also able to use this trail.
This hike didn't quite live up to my expectations, but it was still a good time. Pretty much a straight incline through forest until you finally break out onto the top of the ridge. Awesome views of Mt. Rainier and Mt. Adams, and if the air is clear enough (it was when we went!), Mt. Hood! Mt. St. Helens peeks over the top of the next ridge to the south.
My hiking partner and I were expecting the trail to reach a true 'summit' with 360-degree views of all 4 mountains, but as we continued along the trail we seemed to circumnavigate it. I'm fairly certain we didn't miss a turn-off to another trail, so I don't think there exists a trail to the very top. That was a little disappointing. We wandered along the ridge for a while and ate a late lunch/early dinner on a cool rock outcrop, then headed back down before we lost too much light.
The trail appears well-maintained, although not frequently traveled. My buddy and I were the only people on the trail on a late-July afternoon, which was a little scary for us being that far out in the wilderness. It took us about 2-1/2 hours to reach the 'top'.
We saw a couple of frogs on our way up through the forest, and got the crap scared out of us by a big pheasant (?) that seemed to be guarding a nest in one of the trees near the top. Lots of beautiful flowers (indian paintbrush and pretty purple daisies) and so many berries-- huckleberries, wild strawberries, and all kinds of fluorescent red berries that we figured were probably poisonous.
I'd call this a 'good' but not 'great' hike. The view of Mt. St. Helens and lack of a real 'summit' were disappointing, but it was a pleasant surprise to see the other 3 mountains, and a good leg work out for sure! If you seek solitude, this is a good place for it.