So there I was, on my back, slinking feet first through a hole just 10 inches high. I call ahead to the guide. “There isn’t some crazy abyss on the other side, is there?” After all, I could only see rock inches away from my face, as I had to tilt my helmeted head to the side to make the tight squeeze. His response was not comforting.

“Actually there is, so you’ll want to place your feet exactly where I tell you, then mantle across to the rock saddle that bisects the drop-off, and carefully scootch across on your rear.”