My humble apologies if its been covered before but what are the do and donts of onsen etiquette?

I know a few of them

Wash before you get in.

Cover your bits with a tiny towel. Or not. That seems to be optional.

Don't swim.

Remember not to stay in too long, otherwise it's fainty fainty.

no peeing
no bombing
no heavy petting

Pretty much move around with respect, don't run about the place, give yourself a good scrub before getting in, don't take soap into the bath. The towel over the knob thing, whatever you are comfortable with I have seen locals do both.

I like to rip a good one right when I get in the bath and watch all the bubbles come up. Its also quite a good way to clear a bit of extra room... if you have a bath to yourself, by all means cannonball it man (just be careful not to splinter your ass on the wood below).

>no heavy petting

you obviously havent been to a konyoku nor had a private onsen

Avoid splashing or making waves if there are others inside the furo.

I always wash first, then get in to soak, but I've seen locals rinse briefly with the furo water, get in for a little soak, then get out to scrub, and go back in.

You can cover the dangly bits with the towel, but avoid letting the towel go into the furo water when you get in. I think that's supposed to be terribly bad manners. You see people covering up with towels whilst in the water on TV, but that's only for TV. Best to fold the towel up and put it on your head.

Don't forget to drink some milk with one hand on your hip afterwards!

Put the little (dual purpose!) square towel on your head when you sit in the onsen.

social grooming, just like the monkeys.

Don't go in after they are officially closed.
Don't go in the girl's onsen if you are a boy or vice versa.
Don't spill red wine in the bath.
Don't change the male/female signs around late at night and cause ususpecting old Japanese ladies to meet naked gaijin men early the next morning.

Change out of your nappy and into pants before pay in case the lady asks if you are toilet trained.
Do a big wee wee on the toilet before you go in.
Don't go until you have done your after dinner poo-poo.

Always thoroughly wash before you get into the bath - unless you are a Japanese ojiisan (old boy) in which case a tiny splash of bath water over one shoulder will suffice.

However long you spend in the bath, an essential part of the process is a chill out period in the waiting room afterwards. If you are waiting for women to dry their hair, it could be hours. A massage chair session and beer are obligatory

The beer in the onsen thing is a potential banana skin, I've had onsens with beer but mostly without. My advice would be have a quick look in and see if there are any J-guys drinking in the onsen if there are great, if not then best save the beer till you get out

I leave the beer until after. Tastes great then.

Curious with the drinking though, as some places seem to advertise themselves with pics of the sake bottle and small cups floating on a tray in the onsen. (Or did I imagine that?)

I've seen em like that as well (in the adverts)

Nozawa Onsen completely bans alcohol in the onsen, dont bring any in there. Some places in Hakuba allow alchol, some only allow it when you buy it there (like the sake), and some ban it as well. Hokkaido seems very relaxed, especially when many of the onsen which are 15-45 mins away from Niseko/Rusutsu are basically empty. Kyushu is chilled as well. Guess it depends on the locals (owners) rather than the guests.

I don't think letting one rip will clear space for you either. Plenty sulphur smell already.

I like private onsens rotenburo in posh hotel rooms looking out onto the mountains. With ms zdlfskdladealijfsxdfk sharing the tub of course.

oooh, I dunno, I can brew up quite the nastiness and would give that a fair shake I 'reckon.

Nasty like, "who put the dead animal in the water"?

just don't do the brown wave llke the jacuzzi girl.

That was wild. Perhaps it has a place in this thread