TokyoDome City, a leisure center in the heart of the city, is home to thesesprings, which bubble up from hundreds of feet deep inside the earthinto a network of outdoor baths. From $22. www.tokyo-dome.co.jp/e/laqua/spa.htm

Sykes Hot Springs,
Big Sur, California
Along day hike through a redwood forest leads you to these boulder-linedbaths, which bubble from the ground beside a babbling brook. To getthere, take the Pine Ridge Trail from the Big Sur Station. (831)667-2315

San Antonio Hot Springs,
New Mexico
Locatedin the Santa Fe National Forest, these hot springs flow from a steephillside, creating a collection of soaking baths, each progressivelycooler the farther downhill you go. The hot springs are a five-milehike from the Jemez Springs area in the national forest. (800) 777-2489

Ainsworth Hot Springs Resort,
British Columbia, Canada
Ahorseshoe-shaped cave is a defining feature of these hot springs, whereyou can sit in the cozy darkness of a natural cavern and relax in warm,mineral-rich waters. The hot springs are off of Highway 31, on thewestern shores of Kootenay Lake. Free for resort guests; $10 day ratefor visitors. www.hotnaturally.com