Blue Lagoon

This geothermal lagoon just a short drive from Reykjavik claims healing powers in its mineral-rich waters. One of those only-in-Iceland destinations, the world-famous Blue Lagoon attracts 400,000 visitors annually to its warm, fluorescent-blue waters. (The lagoon's contents are replenished every 40 hours, and its temperature remains a constant 104 degrees even in the most frigid of Icelandic winters.) Encircled scenically by lava rocks and black-sand beaches, the spa's grounds include a restaurant, conference center, and modern locker facility, along with a psoriasis clinic opened in 2005. (The lagoon was first heralded for its positive effects on skin conditions.)