Would it be appropriate to ask to go swimming for a second date?

So I plan to ask a girl out on a second date. Given the ongoing heat wave in Europe, swimming at a beach would be the ideal activity for me. However, I'm afraid she might interpret this as some kind of sexual advance (since normally people don't have much clothing on while swimming).

What do you guys think? Is this a normal thing to do? How would you react to a suggestion like this?