There is a longer version of the loop for those who want a bigger day, but the route mapped here is the typical High Divide Loop. It begins and ends at Sol Duc River trailhead, near the Sol Duc Hot Springs. To recuperate in style after your run, you could book a night at the resort. Reservations are hard to get though, so most people choose to stay outside the national park. However the driving distance from Seattle is reasonable, making it possible to do the whole trip in a day from the city as well.

Starting on the Sol Duc River Trail, you’ll likely share the path with a lot of hikers bound for Sol Duc Falls, but the crowds are quickly left behind on the rest of the loop. If you want to get the brunt of the climbing out of the way early, get your view of the waterfall then follow Deer Lake Lake Trail (as mapped). This takes the loop counterclockwise, going up a steep valley to Deer Lake and then to the divide. The uphill is nicely broken into short sets of switchbacks with flatter sections in between. Rocks and roots are prevalent, and you can expect a fair amount of mud in the forest as well. In the higher elevations the trail dries out, unless it’s still snowy, which is often the case through early July.

The High Divide Trail is certainly the highlight of the run. It’s hard-packed singletrack traversing open slopes and tracing ridgelines at high elevation, among flower-filled meadows and scattered trees. Views are huge in every direction if the weather is clear. You’ll see the glacier-capped Mount Olympus and the deep-cut Hoh River Valley, and more mountains unfolding all around. On the High Divide and on the other trails in the loop, short side trips lead to clear lakes, perfect for taking a quick dip or refilling water (treatment required). After dropping off the divide, the Sol Duc River Trail leads gradually downward through the lush forest, back toward the waterfall and the trailhead.

Sources: https://www.nps.gov/olym/planyourvisit/high-divide-loop.htm http://alittlerunny.blogspot.com/2013/09/the-high-divide-loopseven-lakes-basin.html