Canyons are inherently risky. Flash floods occur without notice on sunny days. Technical skills & surrounding topography knowledge required yet does not eliminate risk.
A Vegas Gamble...Start with Seven, end up with Many
Located in the River Mountains outside Boulder City, Nevada, this lasso-loop hike is comprised of an off-trail scramble up the pour-overs of Seven Falls canyon, a traverse on game-trails over to the head of Many Falls canyon, followed by down-climbs of the numerous pour-overs in Many Falls Canyons. Whether or not there are actually seven falls in the first canyon depends on what you consider to be a pour-over and we lost count of the number of pour-overs in Many Falls. Aside from the fun scrambles, the multiple colors making up the canyon walls were delightful to see.
While we're not experts in the classification of canyons, we've read that both canyons have pour-overs that are considered Class 2 through Class 4. Further, some of the falls can be bypassed, but beware that many of the bypasses looked sketchy in that the rock is loose and crumbly. A handline is useful for lowering/raising packs and/or giving your partner(s) a bit more confidence with the scrambles. We rated the hike a "3" in terms of difficulty only because of the challenging climbing and exposure. Note that this route would be an excellent one for working on partner-assist techniques.
From the parking area behind a brown water tank, hike due west up the canyon. Stay on the far north (right) side of the canyon to avoid a gravel-sorting operation. After about a 1/2 mile, you'll come to the convergence of Seven Falls and Many Falls canyons. Take the right fork (Seven Falls). You'll immediately encounter the first pour-over. While high, it is easily climbed. The second pour-over is about another 100 yards up canyon. It's more steep than the first, but still quite do-able. The third pour-over is even more difficult, but manageable with partner-assists. Continue making your way up canyon, deciding which pour-overs you want to take on and which ones you think you should bypass.
Eventually, the canyon opens up to a wide wash. Keep an eye out for a big cairn on the left. It's here that you'll gradually ascend out of Seven Falls, headed in a southwest direction. Follow game trails along the side of the hill until you get to a saddle with a large cairn. From there, look for a dark brown peak. Aim for the saddle on the east (left) side of the peak. This is a good place to stop for a snack. From this saddle make your way due east down into Many Falls canyon. Note that you can see a wide wash to the south that has electric lines running along it. This is not Many Falls canyon. Another way to look at it is that Many Falls runs west-to-east between Seven Falls canyon and the wide wash. We rated this hike a "3" in terms of route-finding because the traverse from Seven Falls over to Many Falls could easily be confusing. Once in either canyon, though, we'd rate the route-finding a "1". A GPS route and a good map are highly recommended.
Once in Many Falls canyon, you'll quickly encounter the first of its pour-overs. We found all but one to be an easy down-climb and one we chose to bypass (but a more experienced climber could make it). There are particularly wonderful colors nearer the end of Many Falls so take your time to enjoy your surroundings. After about a one and a quarter miles of scrambling in Many Falls, you'll come back to its convergence with Seven Falls. From there, hike down canyon back to your vehicle.
WARNING! Hiking and outdoor related sports can be dangerous. Be responsible and prepare for the trip. Study the area you are entering and plan accordingly. Dress for the current and unexpected weather changes. Take plenty of water. Never go alone. Make an itinerary with your plan(s), route(s), destination(s) and expected return time. Give your itinerary to trusted family and/or friends.