How does Danes not freeze in the sea?
No idea. Danes seem happy with 15 degrees air and same for the sea. I was fine just today, when I came tired and over-sweated from work, I knew, I need to go dive a bit. Since I live 10 min by bus from the beach (Klampenborg strand), and it was way too humid in the air, there was no other thing to do than to go.
Sea turned out to be still a little bit too cold, but refreshing. I enjoyed every second of it.