Shower naked!

That’s the sign hanging by the entrance of most of the amazing geothermal pools in Iceland.

Then you enter the changing room and there it is again, this time with a few more exclamation points: Shower Naked!!!!!

“What is it with Americans, and why do they refuse to wash properly before entering public pools?” a local friend asks me.

“Why do they insist on showering in their swim suits? You can’t wash properly if you shower in a bathing suit, you know.”

I tried to explain that Americans tend to be modest — not to mention self-conscious — about nudity.

“A lot of American kids haven’t grown up seeing their parents walking around naked, let alone seeing other people naked, definitely not in public places. America hardly has any nudist beaches. And they don’t even show breasts on T.V.," I patiently say.

This shocked him, especially the part about American modesty.

“Modest Americans? Isn’t it an oxymoron?” he asked and disappeared in the men’s changing room. That was good news. At least the changing rooms are segregated in most places.

Once I made it to the ladies’ changing room, I was committed to doing my pre-bathing wash properly. Fully nude and dilligently scrubbing.

As I opened my locker, there it was again to remind me: the “Shower naked!” sign. And to prevent all the Americans from cheating by simply “wetting their naked bodies” in the shower for two seconds to minimize their nude time, Iceland got even more specific with the showering requirements here.

This sign came — in several languages — with a diagram of all the body parts “to wash with shampoo” when showering: head, armpits, feet and genitals.

Essentially, any body part that has hair on it (or used to before waxing took off) needs to be scrubbed.

And let me tell you, locals pay close attention. Not to your nudity, mind you. They, mercifully, come in all different shapes and sizes there, too.

But they will make sure you are washing all the proper bits and pieces and don’t bring some awful foreign bacteria into their pool.

People in Iceland don’t take the business of scrubbing their genitals lightly. It’s a several minute cleansing ritual that most people in New York would only subject themselves to before a really, really hot date. And they wouldn’t, typically, do it in public, unless it was a gym known for "that kind of thing.”

So, in case you are planning a trip to this stunning country, be prepared.

Before you venture out to indulge in some of the world-renown geothermal soakage in Iceland, practice the essential six-body-part scrubbing method at home.

Heck, to get into the Scandinavian nudity spirit, maybe you could even invite the neighbors to watch.