It's part of PE (phys.ed) here. It was just like any other class - one morning a week for one school year, you're dragged off down the muni pool.
Perhaps I'm biased from growing up in a coastal town where swimming was a very popular competitive sport and lots of people had boats, but teaching kids in middle or high school is WAY too late IMO, this stuff needs to be taught at a much younger age - like 4-5 years of age.