There is a good photo of the Blue Lagoon in this month's (March 2020) National Geographic. Too bad its not clothing optional there. For having so many hot spring, Icelanders are surprising up tight about nudity. It seems more so there than the other Nordic nations. You have to work hard to find a spot to get naked there.
When I was in Iceland back in the dark ages (90-91 before there was anything at the Blue Lagoon other than the power plant and a relatively small changing shack and snack bar), it was not unusual to see topless women and the occasional totally nude out in the lagoon, and was quite common to see people change right along the edge. I often went nude in the lagoon, keeping my shorts wrapped around my arm. With the steam, you pretty much had to be right next to a person to know one way or the other.
John aka cobeachbum
Icelanders are not naturally uptight about nudity but the anti-nudity rules have been imposed at all the popular visitor places for the sake of the tourist dollar.
That certainly could be, but I was surprised there wasn't at least one commercial clothing optional place. There were a few places to walk into, but to your point. Even those are overrun by textile tourist. I feel for them, it is the same problem at the hot spring where I live (Strawberry Park HS). All that said, and despite it being difficult to get naked in nature there, I loved it there,
Like anywhere, you connect with the locals, they can direct you to the right places. Thus far I have not had great luck connecting with locals ahead of time through TN, but I'll keep trying. Next trip will likely be to Ireland when Covid abates.