It is over 60km from Dong Hoi City to the northwest and is just 4km off the Ho Chi Minh Trail. The prehistoric cave in Son Trach Commune of Bo Trach District is part of Phong Nha-Ke Bang National Park which was acknowledged as a UNESCO World Heritage Site in 2003.
Thien Duong is 30km long and 60m high and its width ranges from 30m to over 150m, and is at a height of 360m above sea level. According to scientists at the British Royal Cave Society, it is the longest dry cave in Asia. Its highlights are unique stalactites in shapes of Bodhisattva Buddha, kylin (unicorn) and phoenix. The cave also has the longest wooden stairway in Vietnam which is over one kilometer long with local authorities expected to extend some more kilometers onto the stairway.