Continuing down the road, near the end, we came to a trailhead for Black Box, which is a crazy deep canyon.
There is a very ominous warning sign at the trailhead!
After reading the sign we decided that we had to take a look at it. So we hiked about 1 1/2 miles to the canyon's edge.
It's really hard to get the sheer depth of the thing in pictures, but looking into it practically gave you vertigo.
Just ask my brother! He felt better on all fours.
On these last few you can see the San Rafael River far below.