Caving · Quảng Bình ProvinceCaving, Tu Lan cave systemADVANCEDRisk: HIGHVND 3-day guided expedition…A network of river caves and jungle treks in the same karst region as Sơn Đoòng, but with far more accessible multi-day itineraries — swims through pitch-black flooded passage, wild camping inside cave mouths, and none of Sơn Đoòng's strict permit cap.View details
Caving · Phong Nha-Kẻ Bàng National ParkSơn Đoòng expedition cavingEXPERTRisk: HIGHUSD 4-day expedition US$3,0…The largest known cave passage on Earth by volume — sections are big enough to contain a 40-storey building complete with its own cloud formations and jungle growing inside collapsed skylights. A strict annual permit cap (only a few hundred spots a year) and a mandatory multi-day expedition itinerary make this one of the hardest-to-book entries on this entire list.View details