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.
This is a picture of sun rays shining underneath water. I chose this picture because I thought it was really beautiful with the streaks that the light made through the water and the shadows that the light created on the sand.