It's tempting to tout this nature bath as the undiscovered alternative to the crowded and touristy Blue Lagoon, but it has some catching up to do. Both spas make extravagant claims about the health benefits of their water and sell a full line of beauty products. (We are testing each line in the Frommer's lab, and will report the results in our next edition.) The waters at each bath are a unique solution of minerals, silicates, and microorganisms; only the Blue Lagoon includes seawater. Yet, while the Blue Lagoon blocks views of its surrounding lava field, bathers at Mývatn commune with the colorful, steaming hills. Though it may seem like a lot of money for a swim, it's the best way to unwind after a strenuous day of touristing, and saunas are included in the admission price. The water remains at a comfortable bath temperature, between 36°C and 39°C (96.8°F-102.2°F). Remove any copper or silver jewelry, which will be damaged by sulfur in the water. Bring your own towel and swimsuit -- rental for each is 350kr ($5.60/£2.80).

Ásta Price offers 30-minute massages for 3,800kr ($61/£30); to make an appointment, call tel. 464-4411. Otherwise the baths offer no spa menu, and locker rooms are like those at any village pool. Ásta also operates out of the Reykjahlíð pool off Hlíðavegur, and runs the holistic health center Magma Essentials, Birkihraun 11 (tel. 464-3740 or 898-9964; www.magmaessentials.com), out of her home in Reykjahlíð, offering everything from 90-minute therapeutic massages to yoga instruction and aromatherapy.