Thunder Mountain is a remote peak in the SEKI Wilderness, in the heart of the national park. It sits at a triple divide where the Kings-Kern Divide meets the Great Western Divide. This triple point separates the watersheds of Roaring River, Bubbs Creek, and the uppermost reaches of the Kern River. It is higher than almost all of the peaks in this vicinity including Mt. Brewer, but is less well-known and climbed far less often due to its remoteness.
The summit features an incredibly airy step over a deep chasm and a class 4 summit block. The register on the summit is an original, dating back to 1945, with the first several parties' names transcribed onto the first few pages (presumeably copied from loose papers found on the summit at the time the register was placed). Update: sadly, this register went missing sometime before 2005.
Thunder Mtn can be most easily reached from the west via Highway 180. Drive past Cedar Grove and park in the large lot at Roads End (literally). From here it is approximately 19mi to Thunder Mtn. Take the Bubbs Creek Trail east to Junction Meadow, then south up to East Lake and then Lake Reflection. Follow the inlet to Lake Reflection to the southwest up past a series of morrainal lakes on the northwest side of the Kings-Kern Divide until just north of Thunder Pass. Thunder Mtn is the unmistakeable peak looming high to the southwest.
There is a $20 fee to enter Sequoia NP from the west. Permits are required for overnight stays in the wilderness. Permits can be obtained from the Park Service at any ranger station. Most convenient is the ranger cabin right at the trailhead at Roads End. They provide both permits and bear cannister rentals. See below for links.
When To Climb
Climbing is usually done May-Oct. Highway 180 is closed during the winter. In early season, there is likely to be considerable snow on the northeast side, between Lake Reflection and Thunder Col, so plan accordingly.
Camping is allowed in most places in the SEKI Wilderness that surrounds Thunder Mtn. The entry point at Roads End is home to habituated bears, and bear cannisters are currently required when entering from there if you are planning an overnight visit. The bears in the Bubbs Creek area are some of the smartest in all of the Sierra, so don't take this requirement lightly. If you plan to camp south of Lake Reflection, your chances of encountering bears is minimal.
"Named by George R. Davis, USGS, in August 1905, when he made the first ascent and placed a bench mark on the summit. (Farquhar: letter form Davis to W. L. Huber, Sept. 14, 1916.)"
- Peter Browning, Place Names of the Sierra Nevada
Although this peak was apparently surveyed at 13,588' for the old Mt. Whitney 15' USGS quadrangle, the new Mt. Brewer 15' has only the 4120m contour surrounding it. The Mt. Brewer USGS 10m Digital Elevation Model puts the summit at 4125m (13,533'), so that's likely closer to the actual summit elevation.