Triangle Lake (Rock Creek)

Drainage: Rock Creek
Approaches: West Fork Rock Creek Trailhead — 8 mi, 6.5 on trail with 1.5 mi off-trail; 2,600 ft up · From Kookoo Lake — about 0.3 mi southwest · From Bowback Lake — about 0.5 mi east-southeast

Elevation: 10,453 feet
Fish: Yellowstone cutthroat (FWP)
Coordinates: 45.11942, -109.59152
Bugs: Minimal on our visit

Getting there

West Fork Rock Creek Trailhead. Drive past the campgrounds along the gravel access road to the main parking area.

FWP puts Triangle at eight miles with the last mile and a half off trail and 2,600 feet of climbing. We did it as part of a four day trip out of the same trailhead, camping at about 9,400 feet and working the upper basin from there.

The hike

Triangle was the second lake of the third day, about three tenths of a mile southwest of Kookoo.

After Kookoo this is a relief. Kookoo sits below the bench and makes you drop 200 feet to the water and climb back out. Triangle sits on the bench, and the walking to it is easy going across open rock. That is true of most of this basin: Bowback, Ship and Marker are all straightforward once you are up top. Kookoo is the exception.

There is no trail on any of it. The ground is open enough that route finding here is about picking a line rather than searching for one.

Triangle is 4.9 acres at 10,453 feet. FWP lists Yellowstone cutthroat.

Bowback is about half a mile west-northwest and is the next water on the loop.

Tips & safety

• Navigation: no maintained paths through this upper basin. Continuous route finding between the bench lakes, though the open ground makes it as easy as this kind of country gets.

• Weather: high country with nothing to break a front. Come prepared for sustained wind or a storm that arrives fast.

• Fishing: FWP lists Yellowstone cutthroat.

• Camping: Triangle sits at 10,453 feet on the open bench, well above treeline, so no timber, no wind shelter and no firewood. The shoreline is rock and at under five acres there is not much of it. We camped a mile and a half south at around 9,400 feet and worked the basin from there.