World's Coolest Hot Springs
Blue Lagoon, Grindavik, Iceland
The Soak: Healing power on a massive scale—literally, as its real purpose is to supply hot water and electricity to 45,000 Icelanders—this lagoon just outside Reykjavik holds 1.6 million gallons of 99°F–102°F geothermal seawater laced with silica, minerals, and algae.
The Scene: With 400,000 visitors annually, Blue Lagoon has a theme-park feel. Still, a soak here is undeniably cool, like a communal pool party of Icelanders and tourists slathering silky silica mud on their faces and bodies.
When to Go: Year-round, but Iceland’s winters are notoriously glum with just a few hours of daylight, while summers are 24/7 celebrations since the sun barely sets.