Grjotagja

 If you think the Blue Lagoon’s blue waters and volcanic rocks make for a pretty backdrop for your soak, they’ve got nothing on Grjotagja, which featured in a Game of Thrones episode—and where you’ll find yourself bathing in hot springs down inside of a cave! (Just make sure you bring a flashlight so you can find your clothes afterwards.) The unfortunate thing about this spot is that the water doesn’t stay a constant temperature, and sometimes it can simply be too hot to bathe in the water. But especially during the winter, it’s frequently possible to take a dip. To visit, make your way to the village of Reykjahlíð. Know that you’ll need to walk the final distance to the caves. Where to Go: Grjótagjá cave, North Island Drive Northwest, Iceland