QUẢNG TRỊ  The world’s largest cave has once again proved nearly impossible to crack. Every slot to explore Sơn Đoòng has already sold out for both 2026 and 2027, further cementing its reputation as one of the hardest adventure tours to secure anywhere on the planet.

The Sơn Đoòng Cave Expedition Tour is widely regarded as one of the planet’s most thrilling adventure experiences, taking visitors deep into the heart of Phong Nha-Kẻ Bàng National Park in what was formerly Quảng Bình Province and is now part of the expanded Quảng Trị Province..

According to the tour operator, travellers hoping to set foot inside the world’s largest natural cave will now have to wait until after 2027, a reality that underscores the enduring allure of this flagship adventure tourism product.

Nguyễn Châu Á, founder and CEO of Oxalis Adventure, the only company licensed to operate the tours in Việt Nam, said that although the 2026 season is still weeks away and expected to begin in late January, all 1,000 available slots have already been taken.

Notably, bookings for the 2027 season have also been completely filled.

The operator said the sold-out status reflects not only the strictly limited number of tickets but also the cave’s unique ecosystem, towering stalagmites and its two spectacular sinkholes, which have made it a dream destination for thousands of adventure seekers worldwide.

The tour requires booking well in advance, often a year or more, through the sole operator, Oxalis Adventure. With strict conservation limits capping visitor numbers at 1,000 per year, securing a place involves a highly competitive online booking process, with tours running from January to August.

 

To book the tour, tourists must meet strict requirements for physical fitness and trekking experience.

Sơn Đoòng lies deep within the core zone of Phong Nha-Kẻ Bàng National Park in Thượng Trạch Commune, about 25km from the nearest road. The approach is rugged, cutting through forests and rivers and navigating complex cave systems. As a strictly protected area, the site is not open to independent travel.

The cave’s vast main passage stretches for more than 5km, with sections soaring up to 200 m high and 165 m wide — dimensions large enough to accommodate an entire 40-storey New York City skyscraper. In recognition of its scale, Guinness World Records named Sơn Đoòng the world’s largest cave in 2015.

Since officially opening to visitors on August 1, 2013, the cave has welcomed 8,552 people. Vietnamese tourists make up the largest group with 3,293 visitors, followed by 2,271 from the United States. Collectively, visitors have spent about US$25.5 million on the experience.

Sơn Đoòng Cave tours have contributed about $5 million to the conservation of Phong Nha-Kẻ Bàng National Park and created 130 direct jobs for local residents, along with hundreds of indirect positions, supporting sustainable livelihoods for communities in the buffer zone.

In recent years, the cave has drawn widespread acclaim from international media. Among the accolades, the British travel magazine Time Out named Sơn Đoòng one of the world’s 10 most beautiful caves.

“Natural caves don’t come much larger than Sơn Đoòng, close to the border between Laos and Việt Nam. This mammoth abyss has the largest cross-section of any known cave on the planet, a vast area that is difficult to describe,” the magazine wrote.

 

“Supposedly, a Boeing 747 could fly through without damaging its wings, but that doesn’t really do justice to the vastness of Sơn Đoòng. The stalagmites here are pretty massive too, with some reaching up to a whopping 70 m.”

The success of the Sơn Đoòng tour has generated momentum for the development of other tourism products in the region. Less demanding itineraries such as Én Cave, Va Cave and Nước Nút Cave have attracted growing interest, helping to diversify offerings and encourage longer stays.

Statistics show that Phong Nha–Kẻ Bàng National Park has become a major global centre for cave exploration tourism, drawing nearly 50,000 visitors each year. VNS