This 20-mile section of the longer 93-mile Wonderland Trail travels along the northern side of Mount Rainier from Mowich to Sunrise, utilizing the Spray Park alternate.
Starting from Mowich Lake, hikers can find the start of the trail around the southside of the campground. The trail quickly splits, and hikers should keep left along the Spray Park trail. After two miles of relatively flat and forested trail, hikers have the option to take the quick 0.2 mile spur trail to Spray Falls before climb steadily out from the river valley via a series of switchbacks.
Once out of the woods, the trail levels off a bit and the meadows open up before you. Soak up this next mile of incredible mountain and glacier view, as well the wildflowers, if they're in season. After reaching it's high point, the trail begins a long descent down to the Carbon River. When the trail splits near the river, keep right to cross via the impressive suspension bridge and rejoin with the Wonderland Trail.
After the crossing, the trail climbs steadily uphill for several miles alongside the Carbon Glacier, finally topping out just before Mystic Lake. At around 12 miles in from Mowich, Mystic Lake is a great location to stop for lunch, or set up camp (if you've snagged a permit for it).
From Mystic, the trail drops down a bit more before skirting around the Winthrop Glacier and resuming the climb. After a few long switchbacks, hikers will reach the top and a junction with the Skyscraper Mountain trail. There are incredible views here of both the mountain and the Lodi River drainage (keep an eye out for grazing mountain goats, too!)
The trail curves along the scenic basin with a few small creek crossings before climbing up it's final, small hill toward Frozen Lake and the Burroughs Junction. It's all downhill from here as hiker's now have the Sunrise Visitor Center in view. Keep right to follow the official Wonderland Trail back to Sunrise, or head slightly left to opt for the Sourdough Ridge route.