Australia.
Do not, do not, absolutely do not go for a swim intoxicated, outside the flags, or both.
Because unless you hail from somewhere like Hawaii, you have no idea what swimming in the ocean is like. That is not the same water as what is in your local swimming pool. It is to your beach in Devon like a raging bull to a tame cow.
Once, on January 1st, on Bondi Beach, I saw lifesavers pulling people from the ocean non-stop. Their jetski was turning at the knee-deep to pass another distressed yet living body to those ashore, and without a pause, racing back to pick another one, then another one, for close to two hours. I’ve heard horror stories about pulling a 140kg Englishman, all covered with a thick layer of tan oil, out of the water.
They need to erect a monument to Australian Surf Life Savers there in the UK, really.
See the flags? Swim between the flags. Don’t see the flags? Don’t swim.