"Crater Lake National Park is a United States National Park located in southern Oregon. Established in Crater Lake National Park is the fifth oldest national park in the United States and the only one in the state of Oregon.
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.