This micro-waterfall had a symmetry that brought to mind the thundering giants of Iceland. It was quite the challenge to stand in cold, rushing, ankle-deep water that made the slabs shake, hold onto my trekking poles, take my tripod off the side of my pack, set it up & hold onto it so it didn't wash away, then slide my pack off my back enough to get my camera out, but not open it so much that anything else fell out (it opened with zippers on the side that would normally be against my back) and attach it to the tripod. And then, of course, to reverse the process after taking my pictures!
These natural tunnels are called "subways". This one is in Zion National Park and is generally just called "The Subway". It can be accessed from the top down, a technical canyoneering route, or bottom up, a hike in with many river crossings. When I went in, the NPS site said to expect knee deep crossings, so on the first crossing, as described by the on-line guide I had printed out, I left the top of my waders down. When I was in mid-thigh deep water, I wondered if I had made a mistake, but couldn't put the top up then as my pack was in the way! Fortunately, it didn't get any deeper, and on the way out I found a much better route where I was no more than knee deep on any of the crossings.