1184-4244 - Aerial of the Song Con River with the limestone mountains in the background, Phong Nha-Ke Bang National Park, UNESCO World Heritage Site, Vietnam, Indochina, Southeast Asia, Asia

1184-4239 - Colourful Paradise cave, Phong Nha-Ke Bang National Park, UNESCO World Heritage Site, Vietnam, Indochina, Southeast Asia, Asia

1184-4238 - Colourful Paradise cave, Phong Nha-Ke Bang National Park, UNESCO World Heritage Site, Vietnam, Indochina, Southeast Asia, Asia

1184-4241 - Aerial of the Song Con River with the limestone mountains in the background, Phong Nha-Ke Bang National Park, UNESCO World Heritage Site, Vietnam, Indochina, Southeast Asia, Asia

1184-4243 - River boat on the Song Con River with the limestone mountains in the background, Phong Nha-Ke Bang National Park, UNESCO World Heritage Site, Vietnam, Indochina, Southeast Asia, Asia

1184-4242 - Aerial of the Song Con River with the limestone mountains in the background, Phong Nha-Ke Bang National Park, UNESCO World Heritage Site, Vietnam, Indochina, Southeast Asia, Asia

1184-4240 - Colourful Paradise cave, Phong Nha-Ke Bang National Park, UNESCO World Heritage Site, Vietnam, Indochina, Southeast Asia, Asia

1176-862 - Son River and Catholic Church in the Phong Nha Ke Bang National Park, Quang Binh, Vietnam, Indochina, Southeast Asia, Asia

1176-863 - The illuminated interior of Paradise Cave in Phong Nha Ke Bang National Park, Quang Binh, Vietnam, Indochina, Southeast Asia, Asia

1176-865 - Sunset over the Son River in the Phong Nha Ke Bang National Park, Quang Binh, Vietnam, Indochina, Southeast Asia, Asia

1176-864 - The illuminated interior of Paradise Cave in Phong Nha Ke Bang National Park, Quang Binh, Vietnam, Indochina, Southeast Asia, Asia

857-86795 - Cave explorers illuminate a large passage in Hang En, Phong Nha Ke Bang National Park, Vietnam.

857-86794 - A cave explorer stands beside a large stalagmite in Hang Son Doong, Vietnam.

857-86800 - A cave explorer overlooks camp for the night from a high vantage point in Hang En, Phong Nha Ke Bang National Park, Vietnam.

857-86807 - A cave explorer illuminates a large passage looking out towards the second doline in Hang Son Doong, Vietnam.

857-86791 - A cave explorer on a speleothem at the first doline, or skylight, in Hang Son Doong while two other explorers illuminate a large passage leading to the second doline 1.5 kilometers away.

857-86805 - A caver is dwarfed by massive stalagmites in Hang Son Doong. Light can be seen coming in in the distance through the frist doline which is over 3 km away. Hang Son Doong is located in Phong Nha Ke Bang National Park, Vietnam.

857-86804 - Cave explorers make their way to the exit of Hang Son Doong.

857-86797 - A caver stands in a sunbeam coming through an entrance to Hang En Cave in Phong Nha Ke Bang National Park, Vietnam. This natural phenomenon occurs only in the months of December and January.

857-86798 - A caver stands in a sunbeam coming through an entrance to Hang En Cave in Phong Nha Ke Bang National Park, Vietnam. This natural phenomenon occurs only in the months of December and January.

857-86803 - A cave explorer crosses a fast flowing river in Hang Son Doong, Vietnam

857-86799 - Hang Son Doong, located in Phong Nha Ke Bang National Park, Vietnam, is home to a high quantity of rare cave pearls.

857-86802 - A cave explorer stands on rimstone formations in Hang Son Doong, Vietnam.