This image looks almost comically serene — and that might in fact be the whole point. This is a security forces Airman shortly after being plunged into a pool as part of his Pre-Ranger Training Assessment Course.
This is just one of the parts of a test that Airmen form the Front Range area undergo to determine if they're physically and mentally ready to attend the Pre-Ranger Training Assessment Course. Which is in itself a test to see if they're ready to attend the US Army Ranger School at Fort Benning. Nobody said it was going to be easy, I suppose. Also, it is reminiscent of the cover of Never mind, isn't it?