Oedo-Onsen Monogatari (Tokyo): Hot water pumped from the deep supplies this unique hot-spring bath, modeled after bathhouses of the Edo Period. A visit here is both relaxing and a cultural experience.

Hakone: Hakone abounds in hot-spring spas and ryokan along the old Tokaido Highway, which originated to serve the needs of feudal lords traveling to Edo (now Tokyo). Its proximity to Tokyo makes it my number one choice for a weekend hot-spring getaway. The most famous public bathhouse in Hakone is the state-of-the-art Yunessun, with its wide variety of indoor and outdoor baths. The timid should take heart -- you wear a bathing suit to most of them.

Spa World (Osaka): You could easily spend a whole day at this lavishly decorated, international-themed, hot-spring bathing facility: Travel the world with a bath in the German sector, a sauna in the Finnish room, and an outdoor soak in the Japanese area. Swim in the rooftop pool, relax on the sun terrace, and have a massage.

Thalassa Shima: Set on the dramatic coastline of Ise Shima Bay, this modern resort combines the Japanese love for taking the waters with French thalasso therapy (seawater, sea mud, and seaweed treatments). A pool overlooking the bay, rooms with seaside views, and French and Japanese restaurants make this a great sophisticated getaway.

Dogo Onsen Honkan (Matsuyama): Located in Japan's oldest hot-spring spa, this century-old bathhouse gets my vote for the country's most delightful. It's a wonderful traditional wooden structure with baths and a communal tatami area where you can relax afterwards in a yukata (cotton robe) and drink tea. It's all very civilized.

Beppu: This king of hot-spring spas offers 168 public bathhouses and baths in water, mud, and sand. Suginoi Palace is Beppu's most elaborate -- huge pools of various sizes and temperatures. Takegawara Bathhouse, built in 1879, is the place to go for hot black sand -- you'll be buried up to your neck.

Nyuto Onsen: This valley in Tohoku's Towada-Hachimantai National Park is about as remote as you can get, with a string of rustic Japanese inns and outdoor baths nestled in the wooded hills. Difficult to get to, but an experience you won't easily forget.

Noboribetsu Onsen: Hokkaido's most popular resort and one of Japan's best-known spas, Noboribetsu offers 11 different kinds of hot water. Foremost among the many public bathing facilities is Daiichi Takimotokan, with some 20 pools.