the organic bag of water stands a good chance of spreading its dna sequences if he/she engages to similar bags of water standing semi-naked in front of them (which can lead to exchanges of dna information to create an egg ,which in due time will get out and continue the propagation of the species)

worst case, its a pleasant experience for the brain to see specimens of the opposite sex which can be better seen this way than in a city with lots of clothes

that accounts for a significant percentage of people that like the beach (raises hand)

also you can do lots of water sports after which you can take place in social exchanges around a beverage composed of wheat/barley and hoops.