Running a vertical K on Mailbox Peak

I continued my string of mountain runs of increasing difficulty, this time choosing Mailbox Peak via the new trail. With over 4000 vertical feet on the ascent, this was by a pretty wide margin my “tallest” mountain run to date. The European running event called a “vertical K” ascends a mere 1000m , or 3280′ – I blew through that before even catching sight of the summit on this run.

Mailbox Peak

4822′ peak elevation

9.4 miles RT

4300′ vertical gain

GPS track (absurd)

Mailbox Peak used to be notorious for the steep, slippery trail that ascended straight up the mountain in 5 miles round trip. Prospective Rainier climbers would load up their packs and climb the mountain for training. Fortunately, the Washington Trails Association has helped construct a new trail, which reduces the gradient with many switchbacks low on the mountain. The trail just opened up last month, and it is a joy to run on!

The namesake Mailbox

This run was supposed to be a training run as I prepare for the winter season. I am hoping to enter a ski mountaineering (“skimo”) race this winter, so I need to keep up the climbing strength I’ve developed hiking and running this summer. I’ve been slowly working my way up the I-90 hiking peaks, starting with puny Squak Mountain in the Issaquah Alps, to Rattlesnake Mountain, a stout effort at 3k’ gain and 12 miles round trip.

I took off from the parking lot pegging my heart rate right in my anaerobic threshold range of 173-177. The lower trail is covered in leaves from the deciduous forest that thrives at these elevations. The middle two miles of the trail are nice switchbacks in coniferous forest. My biggest problems were a nagging Achilles tendon and my sunglasses, which fogged up with the combination of sweat and the fact that I was literally running in a cloud.

The trail breaks out onto the ridge just before mile 4 and then climbs much more steeply, gaining around 900′ in half a mile. This portion of the trail was not graded like the lower switchbacks, with trail surface varying from mud, to muddy roots, to rock chunks and dirt clods. I hit the mailbox 1:26 after leaving the parking lot, then enjoyed the views through the gaps in the clouds.

After very carefully negotiating the steep upper mountain, I opened the throttle up on the way down, descending to the parking lot in around 50 minutes. The new trail runs VERY fast on the descent!

I was pretty pleased with this GPS track log… looks like I was climbing at roughly 3000’/hour.


I’ll probably be back to this mountain repeatedly. It’s only about a half hour from Seattle, has a great view, and is the perfect length for a hard training run. I have heard that a multiple time winner of the Seattle Marathon ran this in 0:55, so maybe if I magically develop a freakish VO2max maybe I’ll give the record a go one of these days…

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