Perhaps a compulsory school assembly then. about large open water and how cold the water is, and how to float, what to do/lookout for.
My school does this.
I think rather than more campaigns what we need is to make sure that kids learn to swim and receive some awareness of potential dangers as part of the school curriculum.
And swimming lessons are already part of the school curriculum.
But we also teach extensively about the dangers of chatting with strangers online, keeping your info/passwords private and malicious communications.
And, yet, we still have to deal with incidents every year because we're not parents and we can't be there at home to remind them and (some) kids think they're invincible and it won't happen to them and that adults are lame and out of touch, don't trust them and just want to spoil their fun. And some parents don't see a problem either.