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Boulder Grand Pass and Thunder Lake Trail

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Rocky Mountain National Park

Boulder Grand Pass and Thunder Lake Trail is a 15.2 mile moderately trafficked out and back trail located near Allenspark, Colorado that features a lake and is rated as moderate. The trail offers a number of activity options and is best used from April until September.

Length 15.2 mi Elevation gain 3,750 ft Route type Out & Back

Backpacking

Hiking

Nature trips

Walking

Bird watching

Forest

Lake

Views

Waterfall

Wild flowers

Rocky

Scramble

Washed out

Off trail

No dogs

Description
Waypoints (1)
Tips

Reservations to enter the park will go on sale through Recreation.gov at 8 a.m. Mountain Time on Thursday, May 28. Reservations will be available to enter the park from June 4 through July 31. The next release will be on July 1, for the month of August and any remaining days that have not been booked for July. On August 1, reservations will be available for the month of September and any remaining days that have not been booked for August. On September 1, reservations will be available for the month of October and any remaining days in September that have not been booked. Permits issued using the reservation system will allow park visitors to enter the park within two-hour windows of availability between 6 a.m. through 5 p.m. This process will facilitate advance payment of entrance fees, minimize contact between park entrance station staff and visitors and limit congestion in parking lots. The permit system will apply to all areas of the park. In the initial opening phase, the park will open approximately 60 percent of the park’s maximum parking capacity or 4,800 vehicles (13,500 visitors) per day. Boulder Grand Pass in Rocky Mountain National Park. Start at the Wild Basin trailhead, follow the well-signed trail up to Thunder Lake. At the ranger hut, follow an obvious but unmaintained trail around Thunder Lake and then up to Lake of Many Winds. From there, make your way around the boulderfield, then up through the obvious chute (to the right of the triangular snowpatch) to the pass. Note that this last bit is steep (400 ft of elevation gain in 0.15 miles) and it's a nasty, loose, scree field.

Start early, this is a very long hike and plan to be well below treeline by noon. Afternoon thunderstorms abound in this area.

Weather
UV Index
Daylight
Reviews (9)
Photos (668)
Recordings (9)
Completed (71)
Craig Jones
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Hiking

Only went to Lake of the Many Winds. Despite being officially abandoned some time ago, trail still in pretty good shape. A little sketchy going around the snowfield near 11,000'. Once out of the forest, some really great flower fields. Had winds from the east (unusual) so was kind of calm at the lake. With suspicious clouds, decided not to try the pass. One little stretch getting up the first topographic step requires some use of hands, otherwise just a steep slog to get to the lake.

Sarah Webb
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HikingSnow
First to Review

Hiked to Lake of Many Winds and over Boulder-Grand Pass on July 2nd. Thunder Lake is mostly clear of snow and mud except around the outlet. No snow until treeline, then one extensive snowfield and several smaller ones to cross in the next half mile or so. They are easy to traverse if you’re comfortable on snow. We had sturdy boots and hiking poles, no microspikes. At Lake of Many Winds, there is a snow field to traverse on the north side of the lake. There are ice rills, so be careful with your footing. The steep gully to the pass is completely clear of snow/ice, but still sucks to climb. Very glad I didn’t have to descend it, and I’ll probably never climb it again with a full pack. Otherwise, a gorgeous and wonderful experience!

Ryan Powell
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Hiking
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Snieguole Radzeviciene
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Walking
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Ashley Carter
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Hiking
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Vince Gerber
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Hiking
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Dave Wehrs
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Hiking
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Jose Corona
Yellow StarYellow StarYellow StarYellow StarYellow StarYellow StarYellow StarYellow StarGray StarGray StarJuly 14, 2018
Hiking
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Ashley Carter
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Hiking
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