A popular route in the northwest corner of Mount Rainier National Park — try this one as a day hike, an overnight (be sure to get permits first) or as a trail run!
From the Mowich Lake Campground, walk alongside the southeast side of the lake, passing a small shelter before turning away from the lake and heading towards Knapsack Pass, 1.2 miles from the trailhead. Along the way to Knapsack Pass, you'll climb gradually and pass bootpaths leading to Fay Peak and First Mother Mountain.
Descending out of Knapsack pass, meander through open meadows and pass more bootpaths, these leading to Mount Pleasant and a network of trails leading through Spray Park.
Though the trail here leads you around Spray Park, you'll get to traipse right through Mist Park and Seattle Parks; make time to enjoy the flowers and scenery here, especially if you're visiting in the spring.
After the parks, the trail descends to Cataract Valley Camp and on past a turnoff for the Carbon River Camp (permits required for both). Shortly past the Carbon River camp turnoff, you'll cross the Carbon River and link up with the Wonderland Trail briefly.
Turn left onto the Wonderland and hike for 1.1 miles, to another junction, this one with the Northern Loop Trail. Turn left again, staying on the Wonderland, cross the Carbon River (twice!) in half a mile, and then parallel the river along a trail at the base of a hillside for 1.7 miles to a junction where a right turn would take you to Ipsut Creek campground.
Stay on the Wonderland here for 3.4 miles, walking along a river valley and then climbing up to Ipsut Pass. In the pass, stay on the Wonderland (a right turn here would take you to Tolmie Peak). From the pass it's another 0.9 miles downhill to Mowich Lake and the trailhead.