Found to be 736m long, Hang E is a cave that is one long swim! During its complete length only one resting spot can be found where you may get out of the water. The passage is usually 10-15m and 5m high which inevitably ends in a sump.
Hang E is the feeder to Dark Cave (Hang Toi) and both caves take an extremely large amount of water in the wet season when Hang Phong Nha river sink can’t take the volume of water. The river sink backs up and the water after rising over 15m in this huge river valley flows towards Hang E and both this cave and Dark Cave then become part of the Phong Nha Cave system. You can visit Hang E, as well as Dark Cave and Paradise Cave, in the 1 day Jungle Boss National Park Tour.