In my early 20's I spent a lot of time at a nude swimming hole just outside of New Paltz in upstate New York. I had been away in college and some friends who attended college locally had found this place and brought me there. When we arrived, they wasted no time getting their clothes off and although I didn't have their comfort level, I didn't want to seem reluctant and so I quickly got undressed as well. Once fully exposed, the coolness of the air underscored the sensation of being nude and I stood for a few minutes surveying the mixed crowd of naked people laying out on the smooth, flat, rocky area bisected by a clear stream. I then proceeded to walk through the sunbathers, enjoying the fact that I was fully exposed and my junk swinging around as I made my way to the water. There was a deep pool and a bunch of people were congregating around the edges and the path down to the water was a little tight and I had to pass close by a number of young fit girls getting out of the water. Everybody was very polite and exchanging greetings and discussions about how long they managed to stay in the cold water. I dove in and swam underwater the length of the deep pool and surfaced and swam on my back in front of the spectators to the place I got in the water. I sat on a rock for a few minutes and then climbed back out with my shrunken parts on full display. Nobody cared.
I only felt self-conscious on two occasions. I was playing chess with one of my friends, both of us fully naked, when a young girl about 8 or 9 years old, fully clothed, suddenly appeared and asked what we were doing. I looked around and saw no one who appeared to be with her. It was a weekday and very few people were around and the idea of being naked in the woods with a child made me uncomfortable. She did not seem at all interested in the fact that my friend and I were naked but she sat down and was quite interested in the game and asking if she could play. Before long her parents appeared carrying all the gear they brought to spend a day as a nude family and apologized for her intrusion. They picked a spot about 50 feet away and a few minutes later the girl reappeared, this time naked. Her now naked father came and retrieved her and I was relieved when she became more interested in their picnic and the water than our chess game.
The second time I was self-conscious was when a group of women in their 60's, part of a bird watching group stumbled upon the spot and were completely flustered by the sight of a few dozen naked people. They simply did not know where to look and so they kept their eyes gazing upward - which prevented them from seeing where the trail picked up on the other side of the stream. I was standing as one woman approached and I offered my assistance. I think she assumed that I was clothed since I spoke to her (if that makes any sense). She replied "oh, yes, please" and looked down and locked eyes on my penis. She was more than flustered and I felt bad that my state of undress was something that made her uncomfortable and embarrassed.