The Loowit Trail circumnavigates Mt St Helens.  The Loowit Trail is used for the course of the Volcanic 50K race, which has produced the fastest times.  We also track unsupported (non-race) times.  Max Ferguson gave a little detail from his unsupported run:

This is a 1680 ft mountain on the Oregon coast near Manzanita.  It climbs over 1100 ft in 2 miles.  It lies within the Northern Coastal Range mountains.  The trailhead sits across Hwy 101.  The trail has rocky sections, rooty sections, smooth sections and a few areas where you have to run through overgrown bushes. The last little section to the summit is basically all rock and requires some careful footing, though there's no real danger of falling off.

This can be run as a Loop or Point-to-Point.

Lisa Green described the Loop:

Started at the Vivian Creek trailhead, summited all 9 peaks, from the final summit of East San Bernadino peak I backtracked to rejoin the main trail and then took the (very overgrown) Momyer trail back down the forest falls road, and ran a short road section back to the Vivian Creek TH.

http://www.summitpost.org/mauna-loa-trail/235751

Gerad Dean briefly described the route for the Summit Trail (starting at around 6700' elevation):

Todd Falker provided some context (7/17/2014):