Mt. Aetna
Grand Couloir
!Climbing mountains is dangerous! Please read the Mountaineering Safety Page and make sure you have a map+compass and can use them effectively. A GPS or cell phone can be very helpful with navigation but you should still be able to use a map+compass in case your device stops working.
 Difficult Class 2 
Snow Steepness: Moderate  
Risk Factors:
Rockfall Potential: Moderate  
Trailhead:Boss Lake
Start:9,700 feet
Summit:13,745 feet
Total Gain:4,100 feet
RT Length:7.50
Last Updated:5/2016


From the intersection of U.S. 285 and U.S.50, just north of Poncha Springs, take U.S. 50 west for approx. 12 miles. Just after the Monarch Lodge, turn right into the parking area for Monarch Snowmobile Tours. Pass their building to find the start of Forest Service Road 230 and a small parking area just beyond the start of 230.


You may have seen it - here's a view of Aetna's Grand Couloir, from Monarch Pass - #1. This classic line should only be done as a snow climb and is skied by many people each Spring. Park in the small, Boss Lake trailhead parking area or across the highway at Monarch lodge and start your day by walking up Forest Service (FS) road 230 - #2 and #3. Pass the turn-off for Boss Lake after 1.5 miles (#4) and continue another mile to reach a corner, where the view opens up to the southwest - #5. Walk around the corner and turn right to enter the large run-out below the Grand Couloir - #6. If you've previously only viewed the Grand Couloir from Monarch Pass, you might be surprised by how low-angle it looks from this vantage but don't be fooled, this foreshortened view cannot hide the fact that there's 2,900' of gain between you and the summit.

Continue northeast across the openness of the run-out and begin your ascent of the Grand - #7 and #8. Pass through a narrow-ish section between 11,600' and 11,800' to reach easier ground, near a slight turn in the couloir - #9. Once above 12,000', the remaining 1,800' to the summit becomes obvious - #10. Continue climbing north - #11, #12, #13, #14 and #15. Between 13,100' and 13,400', the couloir steepens to approx. 38 degrees and is the crux of the route. Above 13,500', angle northeast (#16 and #17) to gain the summit ridge and the top of Mt. Aetna - #18 and #19.



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Route Photos  Print Options

Photo #1
#1: Mt. Aetna’s Grand Couloir as seen from Monarch Pass. Photo by Otina Fox.
Photo #2
#2: Starting up the Forest Service Road 230.
Photo #3
#3: Pass straight through this junction.
Photo #4
#4: At the junction for the Boss Lake trail, stay right on FS 230.
Photo #5
#5: On the road, approaching the clearing at the bottom of the Grand.
Photo #6
#6: In the avalance run-out clearing at the base of the couloir.
Photo #7
#7: Another look at the entire couloir.
Photo #8
#8: Near 11,200’.
Photo #9
#9: Near 11,800’.
Photo #10
#10: Near 12,300’, in the center of the couloir.
Photo #11
#11: Continue straight up the couloir but watch out for snow-loading on your left.
Photo #12
#12: The remaining route to the summit.
Photo #13
#13: Near 13,000’.
Photo #14
#14: Near 13,400’.
Photo #15
#15: Looking down the couloir.
Photo #16
#16: Heading toward the summit ridge.
Photo #17
#17: Just below the summit.
Photo #18
#18: On the summit, looking back over the top of the Grand.
Photo #19
#19: On the summit, looking east toward 14ers Tabeguache+Shavano and 13er Taylor Mtn. (right).
Photo #20

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