This was probably the neatest discovery of this trail, and unfortunately this photo doesn't look ANYTHING like what this really looked like.
This was a narrow, but fairly tall crevice in the rock wall, very dark, cool, and damp. From a crack along the rock this steady stream of water was spurting out, gently and steadily dripping down into the pool of water that was created at the base, which then ran back underground.
It was honestly THE MOST INTRIGUING and captivating scene ... I just sat there and watched it for quite some time!