Secret Lagoon is a geothermal pool with a spouting geyser located at Hverahólmi, near the village of Flúðir in Iceland. The hot spring is heated by volcanic activity underneath the ground and is the oldest manmade spring in Iceland.
The Lava Tunnel Raufarhólshellir is one of the longest and best-known lava tubes in Iceland. Visitors can step inside with a guide to learn about the inner workings of a volcano.
It's just 30 minutes from Reykjavík accessible year-round.