En Cave is the third largest cave in the world, located in Phong Nha Ke Bang National Park, 1.6km long, highest ceiling # 140m, located on the way to Son Doong Cave, 3.5km from Son Doong. The only way to get here is to walk 11km through the forest with many up and down slopes and many streams. On the way, we pass by Doong village. People here use electricity from solar energy and water from streams. . En Cave has 2 water streams, one from the underground stream with cold temperature, the other from the upper stream flowing down with warm temperature, the 2 streams merge together right at the cave to create cool water that can be enjoyed bathing. At the end of the cave mouth is the nesting place of swallows, the number of which can be millions of birds, you can hear their cries along with the sounds of insects, flowing water and wind like a harmony of nature.