Onsen etiquette

Hi everybody,
does any one know if having flip-flops sandals on (like you do by a pool) when going around in a japanese onsen is permitted or you must be barefoot, no exception granted ? I know this may sound silly, but I'm worried about fungi as I had some bad experience when I did'n weare them by the pool where I go swimming.
Thanks for your answer.
Manuele

When you say "onsen" I am assuming the actual bathing area inside the building (of a "ryokan" Japanese traditional inn, or at a spa), going from the locker room to the actual bath, where everyone washes/takes shower, then dips into the water? Then please stay barefoot.

Your slippers may be dirty.
You may slip in the wet area.
I think it is better to be barefooted.

there is usually tatami flooring in the changing area so you must be barefoot or wearing socks. In the actual bathing area you must be barefoot.

The decent onsens are cleaned thoroughly each day with a brush. Choose those. Either way, flipflops are not a good idea, and they may get washed away since there is no place to keep them while you're in the tub.

Think of the other users...they don't want your flip flops in the bath...for exactly the reason that you want to wear them.

Definitely a BAD IDEA. If a Japanese spots you wearing *anything* in the bathing area they are gonna freak out on you.. lol..