But not in a long time, as a kid it was commonplace. As a teen and early twenties back in the 60's and 70's it was a common thing. It's a great way to relax. Good question.
My Mom used to say when she picked me up at my Grandparents (who lived on a country road) that she used to have to catch me and dress me before she could take me home. Me and my cousins male and female were always going skinny dipping.
I'm the one on the left.