I might join a club.

[Zen]

I used to be a swimmer, and I suffered from cramps (which can be kind of scary in the pool) until I realized I needed the same electrolytes, etc, as for other kinds of exercise. If you have something that works for you with running or on the bike, you might try that while swimming, to keep cramps at bay!

Good for you on the club!!

Yup.
Even though it seems counterintuitive you still experience cellular respiration while in the water. And cellular respiration requires carbohydrates, oxygen, and water!