So that day, I did a workout at the gym, and I decided to go to the Sauna after it. When I got into the sauna, there was no one there so I showered in the right shower and got into the Sauna. I was fully alone for the full duration of it, since it was like 14:00 on a weekday. After 10-15 minutes I got out, showered and rested in the Rest room. After some time (it felt like 10 minutes) I heard the voices of 2 girls entering from the other side, the women's changing room. I knew they were girls around my age by they way they talked and maybe they did the sauna for the first time. I heard the shower go off and I immediately realized my chance. (maybe one of them was in the left shower!! naked!) But in this moment (and this is still painful to me to think of) I thought the right thing to do was warn them that someone is coming by opening the door to the men's chaning room so it makes a closing sound. Then I walked to the sauna, and when I passed the shower there was indeed a girl my age in the shower, but she was already done and had put a towel around her waist. I did not see a bikini strap on neither of them, so I am fairly certain I missed out on a hot girl showering.
I walked into the sauna and they looked at me like I was a creep, maybe they didn't know It was a mixed sauna. After that experience I thought maybe it will repeat if I do it often enough, but sadly it never happened again. But I did see a few women over 30 nude, but it's not the same as to seeing someone my age.