World's Biggest Cave...QUANG BINH PROVINCE, VIETNAM - UNDATED: Cavers near one of the entrance of the Hang Son Doong cave in Quang Binh Province, Vietnam.  At more than 200m high, 150m wide and 5km long, this is the biggest chamber in the Hang Son Doong cave in Vietnam. Australian photographer John Spies, 59, spent a week photographing the natural wonder and the tourists flocking to marvel at its beauty.  PHOTOGRAPH BY John Spies / Barcroft Media  UK Office, London. T +44 845 370 2233 W  USA Office, New York City. T +1 212 796 2458 W  Indian Office, Delhi. T +91 11 4053 2429 W