Lower Black Box, San Rafael Swell


Aug 9, 2007
The Lower Black Box is a section of the San Rafael River just south of Mexican Mountain, before the river cuts through the reef. It's a long, narrow stretch of canyon that is infamous for it's high flash flood potential. Several lives have been lost in the canyon over the years when people entered during high flows. It's not a hike to take lightly, which is why it was after several planned trips that our group finally made it down to make the hike over the second weekend of September. There was a nice high-pressure system and the river had slowed all the way down to 13 CFS. I've read that the maximum CFS that the hike can be done safely is 50 or less but have no personal experience.

Here is a map of our route. I accidentally deleted my GPS track so this is just a rough estimate. It is a very long day, roughly 13-14 miles round trip.

View larger map.
Our trip started out as it often does, leaving Salt Lake after work on a Friday evening, racing through traffic, trying to get to the desert. It had been a couple months for me since I'd been down south and I was dying for it. Our plan was to meet gnwatts at the Sinkhole on the Buckhorn Draw Road, just north of I-70.

We arrived just minutes before our planned meeting time and found we had beat Greg there so we wandered around in the dark, admiring the sinkhole and chatting. After a while we wondered where he could be so we tried to make contact with no luck. After an hour, we decided to leave a note and go find a campsite for the night. Good thing I always have a stack of BCP stickers in the glove box!


So we made it out to our camp and set things up for the night when I got a call from Greg. I could barely here him because of bad service but I was able to gather that he had been at the Sinkhole for hours but that he would come to us. A while later, he arrived in camp and we figured out the confusion. We were waiting for him at THE Sinkhole. He was waiting for us at the junction at Sinkhole Flat! He was literally 1/3 of a mile from us, just around the bend the whole time we were waiting!! Doh! :facepalm:

The next day we all piled into my truck and drove the rough, 4WD road to the Lower Black Box trailhead. The first two miles of the hike follows an old road down to the San Rafael River. gnwatts , lostlandscapes and neiloro .

Approaching the river

The San Rafael River. It really stunk here but I laid down in it anyway. I could smell the sulfur on me almost all the way to Swasey's Leap

We crossed the river and started following a path on the other side that would lead us up onto a bench and along the east side of the river until just beyond Swasey's Leap where the route drops back down to the river.

Looking down on the San Rafael River below the Lower Black Box.

Tim getting a look at the mid-section of the Lower Black Box.

Swasey's Leap. At this spot, the walls of the canyon are only about 10 feet across. It was named Swasey's Leap because of a bet between the Swasey brothers to jump a horse over it. Who knows if Sid Swasey actually did it, but that's how it got the name. There used to be a sheep bridge over it but it fell apart and washed away in the late 1990's.

After 5.5 miles, we finally arrived at the river and started hiking downstream

At first we tried to avoid the water and mud. The water was pure brown and it was hard to tell if it was 2" or 6' deep. To add to the fun, there was tons of rip-your-boots-off sticky mud.

The river immediately below Swasey's Leap

drclef below the leap. We stopped here for lunch before continuing into the canyon.

Starting down from Swasey's Leap

This stuff made for some rough walking. I brought one trekking pole and so wish I'd brought a second one. Oh, and full body armor, knee pads, shin guards, etc. This hike is an ankle breaker!


Soon the canyon got deeper and we found ourselves negotiating countless boulders, small waterfalls and various other obstacles. I shot a lot of footage with the GoPro but I'm still figuring out how I want to piece it together, so for now, here are some stills.

There were some long swimming sections



And plenty of knee to waste deep hiking as well. There were plenty of hidden shin-breakers under that water that would sneak up and throw you into the water.

And if the hidden rocks weren't enough fun, we had the mud. There are so many sections of this hike that look like you could just walk the bank and avoid tripping over boulders, but then you run into stuff like this. Thanks to lostlandscapes for shooting this video of me.




As the canyon started to open up, we had a stretch of easier hiking where several springs flowed into the river.

But as we hiked further, the deep mud returned but now it was unavoidable, no matter where in the river we hiked. So it was like knee deep water and calf deep mud. Tough hiking!

The springs kept coming but they were sulfur-laden and smelled awful. It made some cool patterns though.

Some of the sulfur springs bubbled right out of the river like it was carbonated water.

Others flowed in as white waterfalls.

After many hours of hiking, swimming and scrambling, we found the exit and hiked the last two miles back up to the trailhead.

No clouds in the sky; good for hiking the Black Box, bad for sunsets. The light on the reef and Mexican Mountain was nice though.

Looking back down at the San Rafael River Gorge as it cuts through the San Rafael Reef.

After reading this, you might think that I hated this hike. That would be far from the truth, I had a blast swimming and sloshing around. I would be hesitant to recommend it to most though. And if you do it, make sure you bring TWO trekking poles and good ankle support. And I wasn't joking about shin pads! If you've ever hiked the Zion Narrows, it's kind of like that but with sharper rocks and muddy water. But on the upside, you get it all to yourself.

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Excellent TR, nick. The GoPro stills look good. Now that my shins have healed, I'm definitely looking forward to doing this again, but only when it's at least 30 cfs. I think it'll be a completely different (and even better) experience then.
You always know how to make lemonade out of lemons nick. Awesome TR. It's sucks we can't always hit the hike in epic times (like you see in the pictures), but that's what makes it an adventure. I can't wait to return to The Subway and hope to see it under different conditions than I saw it recently.
Awesome nick!!! :twothumbs: The video is the best! Can't wait for your GoPro footage!

All the slot canyons I've did have been dry. What do you guys wear for footwear when doing ones like this that are full of water?
Nice report! Looks like muddy fun. Did you guys have to filter any of that muddy junk?
Good trip and great TR. It was easy and mild when I hiked it. The Upper Black Box is the dangerous people-killer. I started a database of narrows and the flow rate that I have done them at and what the experience was like as well as the prevailing wisdom on minimums and maximums. We probably ought to flesh that out with collaboration. Can you figure a good way to do that here? It wants to be a table or spreadsheet. There are some resources for max's and min's but nothing good for actual experience at other levels.
What do you guys wear for footwear when doing ones like this that are full of water?

Typically, 5.10 Canyoneers do a very nice job in wet canyons. But here in the LBB, with the never-ending depths of sludge to deal with (at least when the cfs was this low), I'm not sure they'd give much of an advantage. The important thing here was to be sure whatever shoes you were wearing were tied up as tightly as possible--the mud was a shoe-eater.
The Upper Black Box is the dangerous people-killer.

I know about at least 2 deaths in the Lower Box (1999). Can't find much on the upper. What happened?

I started a database of narrows and the flow rate that I have done them at and what the experience was like as well as the prevailing wisdom on minimums and maximums. We probably ought to flesh that out with collaboration. Can you figure a good way to do that here? It wants to be a table or spreadsheet. There are some resources for max's and min's but nothing good for actual experience at other levels.

I'll look into it!
Great report and pics Nick.
I wore and older pair of low cut leather hiking shoes, and they worked great. I used my old granite gear pack that has a couple of holes in the bottom to let water out (important).
I have come to the conclusion that people are not meant to be in the Lower Black Box. Every now and then the universe allows us to explore it safely, if you are prepared and ready to suffer a little. The muddy water takes it's toll on your legs and ankles, boulders, submerged branches and drop offs make it fun and challenging. The deep mud rarely lets up and is at it's worst at the end of the hike. I was nearly spent physically and mentally when we left the water at mile 12. But I was stoked.
As an aside, next time it would be easier to exit left (LUC) right after you see the sulphur spring, and hike along the river. My mind was not working properly at the time to realize this. It would have eliminated the last 45 minutes of mud slogging in the stinky water.
As far as which Box is more dangerous, I can't answer that. Anyone can get killed here if you are unprepared. IMO, the upper Box does not match the Lower Box in it's difficulty, variety and beauty. One mans opinion.
I felt humbled and honored to be able to get through it again, and with a great bunch of folks too.
Excellent TR, nick. The GoPro stills look good. Now that my shins have healed, I'm definitely looking forward to doing this again, but only when it's at least 30 cfs. I think it'll be a completely different (and even better) experience then.

It's a lot more fun at 30 cfs until you hit that big log jam, then things get spicy.
Well, the danger and difficulty is absolutely flow rate sensitive then. I hiked it Sept 5, 2003 and it was really casual. Didn't take particularly long and my buddy had taken his two teen age girls down it that summer. I didn't record the flow rate but here is a pic of the start, for comparison. It looks like a bit more water. We didn't have very much swimming either. This river is nearly always opaque - if not brown then gray like the Dirty Devil. I do remember some knee knocking and shoe sucking mud. These things also change a lot with flushing our or filling in during floods and runoff. That is a while ago so my memory might be blunted too.


I will go look for the accidents in the upper (which I have not descended). About 10 years they ran one of the big adventure races through the Swell and it included the Upper Black Box and they had to heli-lift two people out due to exposure and/or injury. My buddy was descending it with his wife when she was swept over the fall near it's big log jam and she was lucky to escape unscathed. There is some REALLY wild footage of yakkers going down the upper which used to be considered impossible. For example (be sure to check out the misadventure starting at 5:21):

Hey Nick, check out the feature spot at the end for a Taco like ours....

Remember, this river can run at over 1000 CFS during high runoff or flood. I have rubber-duckied it through the Little Grand Canyon upstream of the boxes at that level and it is bank over-full up there..
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