Bathing is an obsession in Japan, a religious ritual that centuries ago became both secular and second nature to the Japanese. After spending some time in an onsen, or hot springs bath, you'll know why. As in mineral baths worldwide, the water is said to heal aches and relieve maladies. If you read Japanese, you might be able to figure out what you are healing while you're soaking (there are often signs). But if you are like me, you don't really care. It just feels incredible.

You needn't go far out of your way to find an onsen in Hokkaido. Almost any town on the island has one. Jozankei and Noboribetsu are two meccas for hot springs bathing in southwestern Hokkaido, with dozens of establishments offering both lodging and meals, or just drop-in charges for a soak. Noboribetsu is a bit of a kitschy tourist trap, but it has a grand old hotel, Dai-ichi Takimotokan, with twenty different hot springs baths (81-143-84-3322; onsen charge, $21). In Jozankei, you won't want to miss the super-charming Nukumorino-yado Furukawa ryokan or its gift shop, next door (81-11-598-2345; on­sen charge, $11).

The very best way to experience an onsen for the first time is to ask a friend who knows the ropes to take you. If you're braving your first bath alone, there are books and Web sites to offer guidance. The do's and don'ts are extensive and, when written down, start to make the entire experience seem like a minefield of violations. Take heart. You need go only once to figure it out.

Before your first visit, memorize the Japanese kanji for men and women, so you don't walk in the wrong door. Often, there's a color code to help you out. Blue curtains hang at the entrance to the men's bath, and red curtains at the women's.

Here, the basic guidelines:
1. Take off your shoes or slippers at the entrance to the dressing room.
2. Take off all your clothes in the dressing room and put them in a basket; fold a large bath towel over the top.
3. Take only a small white towel (usually provided by the front desk or sold as a souvenir) into the bathing area. This is your washcloth.
4. Sit down on a stool in front of a hand shower and spigot. Wash yourself thoroughly, from the neck down, with soap and water.
5. Rinse thoroughly with the bucket and sprayer, and be sure to rinse all soap off your stool and shower area.
6. Step into the bath. Do not jump or dive in. Do not submerge your head or shampoo your hair in the tub. Do not bring your towel or soap with you. But you can chat, if you like, and exult, if so moved: "Goku-raku! Goku-raku!"—"It's heaven!"