Type: Trad, 200 ft, 2 pitches
FA: unknown
Page Views: 1,611 total · 8/month
Shared By: Warren Teissier on Dec 13, 2002
Admins: Leo Paik, John McNamee, Frances Fierst, Monty, Monomaniac

You & This Route

6 Opinions

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Access Issue: Temporary Trail and Raptor Closures Details


This route is more a scramble/adventure hike than a climbing proposition. It is however way cool and should be explored if you are ever in the vicinity of the Royal Arch.

Hike to the spring (hopefully you'll try this when it is dry) and hike West into the gaping cave under some chockstones held in place between the 4th Flatiron and the Lower Tangen tunnel. Climb into the cave and climb up a spiral staircase formed by large boulders, way cool!

This will eventually lead you to the top of the chockstones and into a small amphitheater nestled between the Tangen towers and the 4th Flatiron. This amphitheater is very vegetated and not by good weeds either, so watch out for the poison stuff. I did this in winter after the snow had melted, so the vegetation was dead and flatenned.

Once here, you have a choice to continue up some easy (class 4) slabs that will then place you just North of the 5th Flatiron. If you are into rough hiking you can continue up to the summit of Green mountain by squeezing between the 5th and Schmoe's Nose.

For less-adventurous folks looking to experience the tunnel only, as you emerge out of it, hike South via the saddle between the towers and then East back to the Royal Arch trail.


Standard rack.


George Bell
Boulder, CO
George Bell   Boulder, CO
Following this route to the top of Green Mountain is in my opinion the single worst bushwhack in the Boulder area. I recommend exiting early and escaping via the col between the Tangen Towers. People training for the Eco-challenge should do the complete climb daily, however. Dec 19, 2002
There are 2-3 bolted routes in the amphitheater at the top of the tunnel. Does anyone know any information about them? Jan 26, 2003
George Bell
Boulder, CO
George Bell   Boulder, CO
Regarding the bolted routes - see the routes added by Greg Hand last week (under Tangen Towers). Jan 26, 2003
Possibly the worst bushwhack, but the only other people I have seen up there, besides hikers, on the Royal Arch Trail are those who I have brought along for the ride. The view from the top of the upper Tangen Tower is magnificent. It is also possible to use this route as access to the summit of the [Fourth] Flatiron. One might consider long pants for that maneuver, you might get all itchy. REAL itchy! There are also millions of little stickers. Jan 22, 2006
Brian C.
Longmont, CO
Brian C.   Longmont, CO
Did the for the 3rd time and first time without snow yesterday. This route really sucks quite a lot and is one of the worst bushwhacks imaginable. I was surprised at how much thicker the brush is in the summer, and the poison ivy is EVERYWHERE! That said, it really should be considered a must do for the avid Flatiron hiker. The tunnel is cool, and there is a neat upper tunnel as well. You're guaranteed total solitude, it is hard to feel so removed from people, and this route totally does it. Do it, you know you want to. Jul 17, 2013
Glen Charnoski
Boulder, CO
Glen Charnoski   Boulder, CO
This route is quite an adventure. Route finding was fun, as I didn't really read the beta about the route. Quite hard and slick and mossy getting over some chockstones. Good time of year to do it (spring) as the vegetation is trampled by winter snow. The bushwhacking was so bad, I went only to the top of the Upper Tangen Tower, which has quite a nice view of Royal Arch. Apr 9, 2015
Long Ranger
Boulder, CO
Long Ranger   Boulder, CO
I absentmindedly happened upon the lower Tangen Tunnel, after descending the Fifth.

From the base of the East Face, South Side route on the Fifth, follow the bottom of the Fifth Flatiron North for just a few steps until you reach a few large boulders. You'll find a theme-fitting, mini-tunnel through these buddies, which will give you access to descend the base of the Fifth. All other starts of the east face routes of the Fifth are now accessible. Keep hiking towards the very prominent south face of the first piece of the Fourth Flatiron, then swing right to get into the right place to start the Tangen Tunnel descent.

Kind of a really cool way to link up the Fifth and the Fourth. If this isn't the FKT route for something like the Quinfecta, it should be tried, rather than descending from the Fifth back to basically the end of Royal Arch, then running down the trail to the base of the Fourth. Anyways, it would give one just a little more solitude out there, if you're scrambling in the area, as the Royal Arch can be somewhat of a zoo. Apr 23, 2018