7 - 8
FATMAP difficulty grade
In any talk of trips into the Brooks Range, Thunder Valley is often named and often seen in photos, but information about the place is hard to find.
Though not labeled on any official maps, and sometimes called by various names, Thunder Valley and its extension Hidden Valley are well known to local guides and pilots as highly sought-after destinations in Gates of the Arctic National Park. A kind of inner sanctum of the Brooks Range, these valleys splay open the skeleton of the Continental Divide––strata visibly upended into soaring peaks, with ribs of sheer rock protruding at the core––all adorned with streaks of snow, streams of water, and cloaks of tundra vegetation.
Thunder Valley is a branch of the vast Oolah Valley, which is itself buried deep in the range, only accessible by bush flight or a multi-day walk through the mountains.
Within this pristine natural cathedral, visitors find true isolation on the edge of the unknown, and that’s precisely the point of entering the Brooks Range.
To share too much about Thunder Valley would ruin the experience.
Therefore, the track mapped here is only a general route for planning purposes, and is not meant to be followed exactly.
It’s an out and back from Oolah Lake, through Thunder Valley, to a waterfall near the mouth of Hidden Valley.
It is possible to continue farther into Hidden Valley from there.
Oolah Lake can be a drop-off or pickup point for bush flights, or reached as part of a longer trek through Oolah Valley. This route requires camping at least one night in Thunder Valley, though more time would be recommended.
As in other valleys of the Brooks Range, expect difficult hiking over soft and uneven ground, as well as bushwacking and water crossings.
Camping, of course, requires diligent bear precautions and strict Leave No Trace ethics.
Anyone who enters Gates of the Arctic shares in the responsibility for this revered place, and for leaving it as wild and pure as it’s always been. Sources: https://www.nps.gov/gaar/planyourvisit/backpackingandhiking.htm https://www.nateluebbe.com/journal/gates-of-the-arctic-national-park