Explore the ancient caves of Hang Son Doong, Vietnam. Hang Son Doong is one of the largest caves in the world and features a fast-flowing underground river. For spelunkers, exploring Hang Son Doong is the equivalent of scaling Mount Everest.
The Benagil Sea Cave is part of a system of caves that lines Portugal’s southern coast in the Algarve region. This most iconic cave is located just around the corner from a beach in the tiny town of Benagil.