Iceland, a country known for its lava fields and volcanic activity, is the best place to go for a unique lava caving adventure. Step outside your comfort zone and go underground to explore the hidden world beneath you at Cave Leidarendi or Gjabakkahellir. Both caves are filled with jagged rock formations formed through flowing lava that hardened over a thousand of years ago - truly a beautiful work of nature. If you visit during the winter, you'll even get to see some amazing icicles hanging from the cave roof during your unique underworld adventure. The best part? The tour comes with transfers from your hotel in Reykjavik so all you have to do is show up and enjoy this amazing experience.