#4 Grindavik, Iceland
Just a half-hour drive from Reykjavik, Iceland's capital and largest city, you can find total relaxation in a geothermal spa known as the Blue Lagoon. The steamy blue pool in Grindavik was originally part of a lava formation and now hosts a cozy sauna, silica mud treatments and a cave-like geothermal steam bath. And because it's heated by nature, even during the winter, the lagoon stays at a balmy 98 degrees Fahrenheit so you can stay outside and enjoy the gorgeous Icelandic skies.
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