What is the purpose of a swimsuit?

I don’t mean the kind one would wear when going in the water in extreme conditions. I mean a regular swimsuit that one would wear at the beach while on vacation or relaxing from a hard day’s work.

Unless you’re a big fan of tan lines, the only purpose of such a swimsuit is to hide your naked body. And even if you are a fan of tan lines, there are far more interesting tan lines you could get if you created a shape out of some material which blocks sunlight and stuck it to your skin.

In any case, this makes a swimsuit pretty much an insult to man’s ingenuity, i.e. a thing created solely for the purpose of perpetuating the irrational fear of nudity.