The panoramic views from the tops Castle and Basin peaks may be among the most rewarding in northern Tahoe, but the elevation gain from the trailhead that exceeds 1,800 feet is punishing, making this climb a choice for the committed.
The bowl on the north side of Castle Peak is a popular backcountry ski spot, and the Round Valley just over the saddle of Castle Pass from the trailhead is the location of the Peter Grubb Hut. You may encounter crowds of cross-country skiers, backcountry snowboarders, and casual snowshoers, making this trail feel like a well-traveled winter sport highway unless you arrive early in the day.
At the fork almost immediately after the trailhead, take the right fork following the cross-country ski signs (the left fork here is the snowshoe trail to Andesite Peak.) The trail follows the path of a dirt road as it gradually climbs through pine and fir forest. At approximately three-quarters of a mile in you'll have your first views to the three turrets of Castle Peak that are visible to the north. The trail leads past several different color blazes in the trees that mark other trails through this area, though none of them mark the climb to Castle Peak, so you can ignore these. The trail to Castle Pass will be well travelled and clear.
At about 1.25 miles the trail narrows and enters a stand of young pine trees. Here you will begin the steep but short climb to the 7,936-foot Castle Pass, the well-signed intersection of several different trails.
At Castle Pass you'll lose most of the crowds as you veer north and northeast along the ridge and climb toward the clearly visible Castle Peak. Trees soon become sparse and are replaced by sweeping views over Round Valley to the northwest with the Sierra stretching as far as you can see. The climbing becomes strenuous as you begin the approach to Castle Peak, though a number of outcroppings lie along the path that are perfect for taking breaks as you ascend.
The climb will put you atop the western peak, though if you're prepared to take off your snowshoes and do a little bouldering, the 9,109-foot easternmost peak is the highest point of Castle Peak. Be warned that the climb is steep, technical, and should not be attempted in icy or loose snow conditions.
From Castle Peak, I-80 and Boreal Ski Resorts to the south seem small and distant. Immediately below the sheer turrets on the north side is the ski bowl, and to the northwest is the summit of Basin Peak.
Go back down Castle Peak's steep slopes and connect with the ridge that is a direct 1.4-mile path to Basin Peak. The sun and wind here can create cornices of snowpack overhanging the sheer drop down the eastern side of the ridge, so stay along the western slope to avoid any potential avalanche conditions.
It's about a 400-foot climb to the top of Basin Peak from the saddle. Views open up to several mountain lakes, and sweeping vistas stretch in each direction. It's possible for those with backcountry navigational tools to drop into the Round Valley from here and connect with the Pacific Crest Trail (often hidden beneath snow) to return to Castle Pass; otherwise, you can retrace your steps from this summit solitude and head back toward the more populated lower elevations.
There is a small parking area at the trailhead, though if it is full or unaccessible due to ice, you can cross beneath the freeway and park at the Donner Summit Sno-Park, which will require a sno-park pass.
Winter backcountry adventures can be dangerous outdoor activities that pose significant risks as conditions affecting safety (i.e. weather, snowpack stability, avalanche hazard) are constantly changing. Prior to engaging in these activities each individual should get the proper training to make safe decisions and be equipped to use avalanche safety resources and tools. Please visit our Backcountry Skiing and Avalanche Safety post to learn more.