Thompson Peak in the Idaho Sawtooth Range July 31 - Aug 1, 2014

Matthew and I decided to climb Thompson Peak this year. It is the tallest peak in the Sawtooth Range. We hiked to the Lake below Thompson Peak (hereafter called Thompson Lake) on July 31, 2014 so our ascent of Thompson Peak would be easier the next day. Here are a few good links:

Here is map of the driving route from Boise to the trail head.

The Road

The trail head is at RedFish Lake. Redfish Lake is probably the most popular lake in the Sawtooth area and is only a few miles south of Stanley on highway 75. There is information galore on how to get to Redfish Lake so I won't go into any detail. There is a special parking lot for all the trail heads that start at Redfish Lake and the road is paved all the way. I was lead to believe from reading other trip reports that there would be a fee for parking at the trail head, but we could not find any information about it when we got there. We were parked there 1.5 days and did not get a ticket, so I believe there is no fee for parking.

The Trail to the Lake

The way to get to Thompson Lake is follow the Marshall Lake trail. Both the US Forest Service and USGS maps show a good trail from the parking lot leading to Marshall Lake. The trail is very well maintained and there are signs that clearly show the Marshall Lake cutoff that leads to the trail named Alpine Way (which leads to Marshall Lake). As the elevation map shows, except for an abrupt elevation gain at the Marshall Cutoff, the first 4 miles of trail have a comfortable elevation gain with a smooth trail. We went through fragrant sage covered hills, Aspen groves and then pine covered slopes. After about four miles where there is a distinct northerly bend in the Alpine Way trail, there is a clear, but unmarked westerly (left) fork in the trail. That west (left) fork is the trail to Thompson Lake. From that fork on there is about as much elevation gain in the remaining mile to the lake as there is in the previous four miles. The trail becomes very narrow in spots, with steep drop offs as it traverses high above the valley that drains Thompson Lake. Whereas the trail up to the turnoff is very easy, after the turnoff it becomes moderately difficult. I had read reports there was no trail, but we followed an established trail almost the entire way from the turnoff to the lake. The last third of a mile is very open and rocky terrain and leads directly to the lake.


Camping near the lake is difficult because there are steep slopes around the entire lake down to the water, except near the outlet. There are several fairly flat, but rocky sites along the east end of the lake. Several sites had clearly been used and we found multiple fire rings.


Fishing in Thompson Lake seemed like it could have been good. I saw lots of rainbow and possibly rainbow cutthroit hybrid trout swimming around near the shore. Some were probably around 12 or more inches long. Several were rising to feed both times I was down near the water. I tried fishing on Friday afternoon after we returned from climbing Thompson Peak. It was windy and the water was choppy. I tried a few different flys and got some strikes, but never did land a fish. The wind and time prevented me from catching any.

Climbing Thompson Peak

We left camp about 7:30 and started heading toward the saddle between Thompson and Williams Peaks. On the way up we purposely steared away from Thompson Lake to avoid all the deep ravines that fall into the lake. As we approached the saddle we saw some beautiful meadows and cascading water falls. The easiest way to get up and over the saddle is to go toward the north side, toward Williams Peak. There is a glacier to cross. The further north you go, the shorter distance there is to cross the glacier. The snow was soft enough and the glacier is not too steep to prevent a fairly safe crossing without going too far north toward Williams. After that it is simple boulder hopping and gently slopping glacier walking up and around to the west side of Thompson. We knew there was a class 3 route to the top, but were not sure whether it was on the north west or south west side of the Peak. We followed the first (northern most) couloir up and came out near the top, but with one more short pitch to the top. Since we were there, we climbed up that roughly class 5 pitch to the top. The only scary part was the vertical drop on both sides.
When we came down off the top we discovered that the class 3 route was on the south west side of the peak. Oh well, we had a great time going up a different way than we came down. The map showing the routes of our ascent and descent show us ascending the more difficult route to the peak and descending the class 3 route.
We wanted to take advantage of the glaciers as much as possible when coming down and we had a blast skiing on our boots down long stretches of several of the glaciers. It is more aerobic than you might imagine, but is also a lot easier on the knees. We have not had that much fun coming down a mountain, since the time when Matthew and I climbed the Colorado fourteeners Democrat, Lincoln, and Bross, and descended about one thousand feet of small, loose scree on Mt Bross.
We followed some of the small streams toward Thompson Lake on the way down. We knew we would not follow them all the way, because of the very steep grade, but we got some different views of the lake.

This picture
is my favorite from this hike and was taken by Matthew on the way down.


I'm sure lots of people climb Thompson Peak from parking lot to peak and back in one day. Packing in and staying overnight made it much more enjoyable. It is of course beautiful and you will probably not see many other people. We saw only one person climbing the mountain as we were skiing down the glaciers. From the register at the top I gathered that there were usually only one or two groups climbing the peak on any given day. I definitely recommend this climb to all moderately experienced climbers.

Useful links

Leave No Trace.