Chilled to the bone from hours of exploring the moon-like landscape of the Reykjanes Peninsula, where Icelanders believe fairies, or "hidden people," live, the idea of going swimming sounded about as enticing as putting lemon juice on a paper cut. But as soon as I saw the steaming, milky blue lake percolating in a vast field of forbidding black lava rock, I couldn't get into my swimsuit fast enough.

Bláa lónið, or Blue Lagoon, is an otherworldly oasis formed by the runoff from a geothermic power plant, just 45 minutes from Reykjavik. The 100-degree water, rich in minerals like silica and sulphur, bubbles up through the lava rock, and the silica silt clouds the water, and forms a silky, brilliant white mud that coats the sharp lava surface with a thick, smooth covering that looks and feels like bathtub caulk. Looking around, I saw people scooping up handfuls of this snowy white gunk and smearing it all over their skin. (That mud, as it turns out, is renowned for its purifying and healing properties. There is even a skin clinic at Blue Lagoon, where sufferers of psoriasis, in particular, find relief.) When in Rome, or in this case Reykjavik.... So, I slathered the milky muck all over myself and just floated on my back in the hot, velvety brew, letting the heat unknot my muscles, until the mud dried to chalk on my face. I didn’t ever want to get out of that powder blue water, but when I eventually did, my skin really was glowing and soft as a baby chick.