I was in Iceland last summer and quickly lost all my inhibitions lol. At all the public pools and spas you are required to shower butt nekked in a communal shower thing (with multiple shower heads, and girls and guys separate change rooms/showers of course). The kicker is there are shower marshals in that room!! They basically ensure that people are actually washing up before they go into the pool, or they won't let you in/make you do it again.
That is probably the only time I would shower naked with my friends and professor.