Hang Sơn Đoòng (Mountain River Cave) is not merely a cave; it is an entire subterranean world. Officially recognized as the largest natural cave on Earth, this breathtaking marvel in Phong Nha – Ke Bang National Park is a geological masterpiece. Its main passage stretches over 5 kilometers long, with chambers reaching 200 meters high and 150 meters wide. These dimensions are so vast that the cave contains its own internal jungle ecosystems and unique climate.
A World of Immense Scale and Discovery
A local resident first discovered the cave entrance in 1990, but a team from the British Caving Research Association fully explored and mapped its incredible scale in 2009.
Underground Ecosystems: The cave contains two massive collapsed ceilings, known as Dolines. These openings allow sunlight to stream down, nurturing dense, primary rainforests deep within the cave floor. Visitors witness a surreal landscape of trees and vegetation flourishing hundreds of meters beneath the surface.
Giant Formations: You will marvel at the sheer size of the stalagmites, some standing over 70 meters tall. Furthermore, the expedition navigates through vast underground rivers and past unique formations with names like the “Hand of Dog.”
Logistical Challenge: Exploring Son Doong is a rigorous undertaking. The standard tour requires a multi-day (typically 4-day, 3-night) expedition involving challenging jungle trekking, river crossings, rappelling, and technical climbing. This adventure demands a high level of physical fitness and preparation from all participants.
Exclusive Access and Essential Requirements
The Vietnamese government strictly regulates access to Son Doong to protect its fragile environment. Consequently, only one licensed operator, Oxalis Adventure, runs the expedition tours.
Limited Annual Slots: The government grants a highly limited number of permits (around 1,000 per year). This strict quota ensures minimal environmental impact and preserves the cave’s pristine condition.
Booking and Cost: You must book the Son Doong Expedition directly through the official operator’s website, often one to two years in advance due to the high global demand. The cost for the all-inclusive expedition is approximately 3,000 USD per person. This price covers all necessary safety equipment, international safety experts, local guides, porters, food, and permits.
Fitness Requirement: The tour operator rigorously vets all applicants for health and fitness. They require participants to be over 18 years old and demonstrate the physical ability to complete the strenuous trek. You must honestly declare your medical and trekking history during the detailed booking process.
Planning Your Expedition
Plan well in advance to secure your slot for this once-in-a-lifetime adventure.
Tour Season: Tours run exclusively during the dry season, generally from January to August. The cave closes from September to December to allow for environmental recovery and because heavy rains cause flooding.
Arrival: All tours begin with a mandatory safety briefing at the operator’s office in Phong Nha town the day before the expedition starts. Guests must arrange their arrival in the Quảng Bình area (via Đồng Hới Airport or Train Station) accordingly.
