Boulder-Grand Pass West to East route

Boulder-Grand Pass West to East route

Page Type Page Type: Route
Location Lat/Lon: 40.22476°N / 105.66977°W
Additional Information Route Type: Hiking
Seasons Season: Summer
Additional Information Time Required: A long day
Additional Information Rock Difficulty: Class 3
Additional Information Grade: II
Sign the Climber's Log


Perhaps best pass in Rocky Mountain National Park to climb multiple summits and a more challenging Continental Divide traverse than Flattop Mountain, Boulder-Grand Pass offers many options. Boulder-Grand takes you to 12000’, within reach of two summits to the north, Mount Alice and Pilot Mountain, and three to the south, Tanima Peak, The Cleaver and Isolation Peak. For adventurous hikers, Chiefs Head Peak can be added to the northern group, Ouzel Peak, Mahana Peak, and Ogalalla Peak can be included to the south. Boulder-Grand Pass sits well above treeline between the northern slopes of Mount Alice and the mostly flat expanses that hold Tanima Peak and terminate at The Cleaver leading to Isolation Peak. Boulder Grand is usually climbed to from the east via the Wild Basin Trailhead, where a great trail system takes you within 400 vertical feet to the broad pass. The western ascent is more reserved for backpackers and die-hard Grand Lakers, thus receives little attention and does not have a consensual route.

Getting There

From the west, Boulder-Grand Pass is reached by hiking to grassy Fourth Lake, but from there, the route is convoluted. To get to Fourth Lake, the East Inlet trail leads from the West Portal parking lot 5.5 miles and 1600’ up to the shallow Lone Pine Lake. From Lone Pine Lake the trail continues 1.4 miles to an unimproved trail at the western end of Lake Verna. This unmaintained trail will take you through the forest up to the good sized Spirit Lake and shallow Fourth Lake, 8.5 miles and 1900’ up from the TH. The unimproved trail isn’t too bad, though pretty braided in some places it is easy to follow and leads along the north bank of East Inlet to these lakes. However, do try to do any little maintenance that can put the trail on the upkeep. Don’t let this trail disappear back into the woods, it really saves time and energy when you trying to get to where you’re going.

Route Description

Either ascending or descending Boulder Grand to or from Fourth Lake, one thing is certain, there really is no standard, ‘right’ route. Ask a few people about the route to or from Fourth Lake and you will find there are many different ways to go about it. However, two things you will hear from anyone you ask about it are certain; it is steep, and you’re going to be climbing over dead trees. The first of which is unavoidable, you gain 1600’ in little more than a half of a mile. The trees, though, can be only a minor part of the experience with careful route finding. The massive headwall and slope up to it that lie SW of Boulder-Grand Pass have obviously experienced some avalanches within the last few decades, leaving a pretty clear, if steep, route up towards the headwall. From about 11250’, the route requires you to find a clearing, grassy slide or open bench north to an obvious, open grassy drainage that leads to the pass.

From the inlet of Fourth Lake, follow the unimproved trail over a few small streams until you are directly east of the lake. The trail leads past the edge of the marsh on the east side of the lake then back into the forest heading towards Fifth Lake. This is the best time to head off the trail, striking east until you can find any one of several avalanche gullies. These gullies are a bit choked with small spruce trees, but are far better than the thick forests to the north. The gullies are not the large scree slopes that extend towards the Cleaver as you near Fifth Lake, the avalanche gullies have trees, dead and alive, in them and are almost entirely devoid of exposed rocks until the top. Climbing up these gullies is not very difficult, just follow animal trails or a string of clearings up about 1000’ all whilst looking NE along the horizon for one or two small gaps between outcroppings of the headwall and the forest below. These gaps are small grassy benches that take you to much easier terrain. Upon locating these gaps, head in a general direction to them, possibly crossing a patch of boulders and up a steep grass slope. Either gap will do. When you reach them, you can cut over a bit north to a large, gentle grassy tundra slope that takes you to the pass. The pass in itself has pretty good views in all directions, and with Tanima Peak just a few hundred feet higher to the south, those views can become exponentially better.

The descent to Lake of Many Winds can be a little tricky and very loose. You are basically climbing down a sandy gulch over polished granite blocks, then across some ankle twisting scree to the little lake at the bottom. To reach this gulch, walk north across the pass to a gully formed by a rock fin and the mass of Mount Alice. This gully should be pretty obvious, and you should see footsteps and depressions in the sand and gravel. The hike down to Thunder Lake is actually a pretty well marked path that should lead you back to the main trail near the patrol cabin.

Useful Pictures

The avalanche gullyThe avalanche gully
The gapsThe gaps
To Boulder GrandTo Boulder-Grand

The two gapsEither gap is good

Essential Gear

This route is just barely(in my opinion) a class 3 venture, and if you exercise good route finding skills, will not exeed the limits of hiking.

Being a very long day, you will want to have plenty of food and water.



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