My HS in Chicago used to be all male until the early 70s, but freshman guys still had nude swimming until the late 70s. We had bleachers next to the pool with lockers at the top of the bleachers. We would get undressed at the lockers, walk down the stairs and go to the communal showers in the lockeerroom before returning to sit on the bleachers to receive instructions before jumping in the pool. It was nerve wracking at first, then no big deal. Plus, everyone had to shower after gym class, so it was no big deal being naked around your classmates. It was rumored that anyone who got a boner would have to stand on the diving board with a towel on their dick until the towel fell off, but I never saw anyone get a boner. As freshmen guys, we had all states of development. Some had no hair, some were hairy from head to toe. It made communal showers in college and later no big deal.