Rocky Mountain National Park: Thunder Lake to Lion Lake Loop
Find unusual solitude at this popular alpine park on a 16.4-mile peakbagging overnight to the Continental Divide.
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By high summer, most climbs in Rocky Mountain National Park start with long pre-dawn approaches to ensure a return to the trailhead by 12 p.m. and thus avoid afternoon storms. But Wild Basin offers a different look for backpackers. Camp in the designated site at Thunder Lake and get right to the climbing the next morning on this 16.4-mile lollipop loop in the park’s southern section.
From the trailhead, pass wildflower-filled meadows on the way to Thunder Lake. Scramble up scree and talus past lakes and waterfalls to the Boulder-Grand Pass, a smooth point in an otherwise rough ridge. The Continental Divide affords big-time views of Chiefshead and Mt. Meeker to the northeast. Ascend to the summit of Mt. Alice and take in the diving board view over Wild Basin, with 14,259-foot Longs Peak looming over the ridge to the northeast.
Descend carefully along the hourglass ridge. Minimize your exposure by hugging the northern side, away from the precipitous southern edge. Follow the ridge back down toward the trio of sapphire lakes pooling below the divide, and pick up the trail again at Lion Lake 1. Hike east and south to close the lollipop and end at Wild Basin.
INFO For information on permits, current trail and camp conditions, and wilderness guidelines, go to nps.gov/romo/planyourvisit/backcountry.htm
PERMIT A wilderness permit is required for all overnight camping in the backcountry. Reservations accepted ($20 administrative fee for permits during peak season). nps.gov/romo/planyourvisit/backcntry_guide.htm
CONTACT Rocky Mountain National Park, (970) 586-1206; nps.gov/romo
Trail Facts
- Distance: 26.4
Waypoints
TLL001
Location: 40.208505, -105.565478
Thunder Lake trailhead
TLL002
Location: 40.203621, -105.608313
Stay straight. Bluebird Lake Trail departs to the left.
TLL003
Location: 40.213558, -105.623679
Outbound: Fork left and stay on the Thunder Lake Trail. Inbound: Continue straight. Peakbaggers attempting Mt. Alice typically head northwest on the Lion Lakes Trail, which offers a slightly shorter summit out-and-back.
TLL004
Location: 40.222306, -105.645126
Campsites and patrol cabin. Camp here and curve north around Thunder Lake next day, en route to Boulder-Grand Pass.
TLL005
Location: 40.224602, -105.669126
Reach Boulder-Grand Pass after a steep climb over sometimes loose rock. If hiking with a group, switchback and gather at the ends before heading back across the face. This technique reduces the chance of accidental rockfalls.
TLL006
Location: 40.239273, -105.663803
13,310-foot Mt. Alice with views of Chiefshead and Longs Peak. Continue north along the class 3, hourglass ridge.
TLL007
Location: 40.244977, -105.660414
Turn south and follow the ridge back toward Snowbank Lake.
TLL008
Location: 40.230431, -105.638785
Reach Lion Lake 1 after passing Lion Lake 2 and numerous cascades. The meadows around here burst with wildflowers in July and August. Follow the Lion Lakes Trail south from here.
