Grindavik, Iceland

No other swimming experience on earth can compare to the Blue Lagoon for dramatic beauty and strangeness. This natural-formed lagoon is so large you can get lost in it. Even though there are usually busloads of people there, the lagoon monitors warn you not to drift too far away from the shore. The water steams into a thick mist and the Icelandic wind blows icily around your head, while your toes barely graze the rough natural rock below. Slather yourself in therapeutic mud, book a treatment in the spa area off to one side, or float over to the booze booth and grab a beer to sip in the shallows.

Lena Katz is the senior travel correspondent for JustLuxe, covering trends, tastemakers, news and more.