AA6XA first activated Thunder Mountain on 14 October 2017. His write-up is a great description of the area and his ascent from the east of the mountain. You can find the link to his write-up on the SOTAmaps Summit page. Ignoring his mention of “cliffs” I opted to plan a route from the west. The directions below describe the drive to the beginning of the west ascent. I knew the climb would be steep, but it would only be around a half mile (.53 to be exact). This is a total bushwhack from bottom to top. From where I parked there is a fence just south that appeared to go to the summit. No such luck. Even if it did, the brush and trees were so thick there would be no way to follow it. I zig-zagged about a ¼-mile up until I encountered the first “cliff.” It wasn’t so much a cliff, but a very steep climb through massive boulders interspersed with rock fall. It wasn’t that difficult to find my way over these and it was actually easier than bushwhacking through the trees and bushes. This scenario played out multiple times until I arrived at what I thought was the summit. It turned out to be a false summit at approximately 7,335 ft (42.17163, -113.61526). There is a small saddle between the two summits. The distance between them is around .10 miles (525 feet) and after dropping down to the saddle the elevation gain is only another 80 feet (7,455 ft). As AA6XA mentions, the views are incredible. From the summit you have 360-degree views of the valley, Cache Peak to the West and down into Castle Rocks State Park. In the distance you can see City of Rocks National Reserve. I tried to pick a safe way back to the Jeep, but it was slow going through slots in the rocks, the heavy undergrowth/trees and the steep terrain.
Directions: From Elba-Almo Highway (Hwy 77) turn west at (42.15981, -113.57327). There are no signs identifying this intersection. The road is very rough (exposed rocks) and rutted. Definitely NOT Prius friendly. I think a Subaru Outback would do alright with robust tires and some meticulous tire placement. You’ll encounter a barbed wire gate at (42.16914, -113.58961) after just under 2-1/2 miles. There is a lever on a chain that you’ll need to use to release the gate to move the fence and then put it back. On my way back, a bunch of cows were hanging out at the fence. I tried to get them to move, but they apparently were on a different schedule! Another patience lesson. Once through the gate there is a Sawtooth Forest road sign (FS 708). My Gaia app calls the road Grape Creek. Continue on FS 708 for about 1-1/2 miles (42.17734, -113.61701) and then turn south/left off of FS 708. Drive a few hundred feet and there’s a small creek crossing. I assume this is Grape Creek. The south bank is steep, but short (maybe not Outback friendly). To be safe, I shifted into 4L and made it through the creek and up the bank with no issues. From FS 708 continue on this road for ½ mile until it fizzles out (42.17352, -113.61937). This is where I began the ascent.
