Should you wear underwear?

Don't wear it. It's better for you.

It is down to the individual whether or not they wear it. Some may think it more comfortable to wear it whilst others may feel better without it.

It is more sensible not to wear it. Underwear is too over rated. Don't wear underwear. Be cool.

The reason for underwear is to keep you hygienic and clean. If it's being cool and sensible not to wear it then the World has gone mad !
No. You wear a swimsuit without anything under it. In competitive swimming, if a judge thinks you are wearing a second suit underneath the first, they can disqualify you from the entire meet.