You sure that wasn't the nude sunbathing?
Off topic (or not): One of the funniest things I've seen was a couple camped across a small lake from where my troop camped in the Sierras back when I was a Boy Scout. Those two were enjoying the lake au naturale for most of the first day after they arrived. Of course, as a bunch of adolescent boys, we were snickering about their bare butts going in and out of the water. Then, about 4 hours later, we noticed that their butts were much, much redder than they had been earlier. We didn't see much of them the next day as we noted that the UV is much more intense at higher elevations.