So I live in an apartment complex with a community pool in the middle. And my bedroom window happens to have a nice view of the pool. The other night around 3am I heard someone swimming with the small waves of the water moving back and forth. I’m a nosey person so decided to get up and take a look. And yep it was a couple skinny dipping taking a few laps around cuddling/hugging each other. Cool of them to experience. But before they got out. Of course he he had to take a seat on the steps and she went for a little ride on him for about five minutes . . . . .
Wife and I have left our butt-prints in the sand of about half a dozen beaches, had outdoor sex dozens of times over the years, and been "skinny dipping" (including sex) 4 or 5 times. We have never flagrantly "put on a show". In fact we carefully chose the times and locations so as to minimize the the chances of being observed, especially by children, but we were always aware that we might be seen.
The only time I'm aware that we were observed was in the late 1970's at a beach in the Florida panhandle. This was a strip between the highway and the Gulf, with perhaps 10 - 15 picnic tables and parking for a couple dozen cars. There were ocean-front motels a quarter mile or so in each direction. We were there in the afternoon and evening, laying on the beach, playing in the water and enjoying a picnic. At twilight the place emptied out except for one or two other couples, up by the cars perhaps 50 yards from the water.
We were still on our beach blanket, making out on the sand. We didn't intend to have sex or plan for it - everything was spontaneous. After it was quite dark we briefly talked about it and decided to try. We waded out to waist-deep, probably 40 - 50 yards, and slipped out of our swimsuits. Unfortunately, the salt water washed away all the natural lube and I couldn't get into her. So we walked back toward shore until the water was just a few inches deep. I squatted down and she lowered herself onto my lap, facing me. Then I stood up, holding her, and walked back out to waist deep.
I think she had the better experience. She could stretch out and lean back, floating in the water with minimal support from me, while we were touching at only our genital connection. A gentle wave action lifted her up and down as she rode me. She moved and squirmed to make it feel "just right", and she splashed and thrashed when she climaxed while floating freely.
It took at least 20 minutes for us to have sex. She was facing mostly out toward the gulf, while I looked toward the beach. I saw two couples strolling on the beach during that time. One stopped briefly while the other stood looking in our direction for several minutes. I'm sure all they could see were some shadowy figures out in the water. Even if they figured out what we were doing, most of the imagery would have to come from their imaginations rather than clear pictures. I never felt embarrassed or threatened. I recall wondering if the couples on the shore would come out and join us but there was no indication they even considered it. Of all the times we have had sex (a few thousand, at least) that is still one of the top dozen times in my mind.