To make this hike a little more interesting – as well as difficult – we climbed Thunder Mountain then walked over to Thimble Peak on the ridge above Kirkwood to the south. At 9805’, Thimble is about 400’ higher than Thunder, but a couple decent drops along the ridge make it all add up to about 800’ and 4 miles of extra hiking. The route to Thimble starts at the Horse Canyon Trail junction just below Thunder, then basically follows the ridge except in a couple places where it dips below on the west side to avoid large rocky outcrops. There’s not really a trail, but a faint footpath can be followed most of the way—nothing tricky or dangerous, just more miles and more climbing. At the summit there’s some moderate scrambling, though we avoided the actual highpoint in favor of sitting atop an adjacent spire that looked no more than 5’ lower. I’m too old (and too wise?) to try Class 3 climbs these days, and Thimble’s real summit blocked looked particularly harrowing. Nonetheless, we felt like we were sitting on top of the world and views in all directions were marvelous. Adding Thimble Peak to the standard Thunder Mountain hike made for a moderate-paced hiked that clicked in at 7 hours, 11.8 miles and 2851’ of elevation gain. A strenuous but highly recommended option.