Divers make surprising discovery inside world’s biggest cave

A team of divers who went to explore the world’s biggest cave in Vietnam have discovered a hidden passage never seen before.

A trio of British divers have discovered a hidden waterway inside the world’s largest cave after venturing deep inside the Son Doong in Vietnam.

The expedition — which was led by the same divers who helped save the trapped soccer team in Thailand in 2018 — swam deep in to the cave before discovering a “groundbreaking” new underwater tunnel never before seen.

The divers ventured in to unexplored parts of the Son Doong cave in Vietnam.

According to CNN, the divers found a tunnel that connects Son Doong (meaning “Mountain River Cave”) with another cave called Hang Thung.

“It would be like someone found a lump on top of Mount Everest, making it another 1000 metres higher,” Howard Limbert, one of the cave experts who helped organise the dive, told CNN.

British divers Jason Mallinson, Rick Stanton and Chris Jewell were part of the expedition. Picture: AFP

The world's biggest cave Hang Son Doong is located in the heart of the Phong Nha-Ke Bang National Park in Vietnam.

“Any cave in the world will be able to fit comfortably inside Song Dong when it’s connected. It’s just outrageous in size.”

Son Doong is located in Central Vietnam in the heart of the Phong Nha-Ke Bang National Park. Based on volume, it’s considered the largest cave in the world and was only discovered by accident in 1990 before being explored in 2009. The cave was opened to tourists to visit in 2013 through a single tour operator, Oxalis.

The cave is thought to be around three million years old and almost 5km long.

It stretches more than five kilometres.

Mr Limbert said the divers — Jason Mallinson, Rick Stanton and Chris Jewell — were invited to the cave by Oxalis after doing such “an amazing job” rescuing the soccer team in Thailand.

“We invited them on a trip to Son Doong to thank them for their great effort,” Mr Limbert said.

“They wanted to do something interesting during the trip, so we came up with this idea of diving Son Doong, which had never been done before.”

Mr Limbert said when the divers reached a depth of 78 metres, they were able to measure some of the uncharted tunnels within the cave.

The cave was only opened to tourists in 2013.

“Now that we know how deep it is, we’ll bring the special gases (oxygen-helium mixture) with us next time to enable long, deep dives,” he said.

“I think it’s incredible that something as important as the world’s largest cave is still being explored and better understood.

“No one had ever set foot inside Son Doong until 2009 … and this latest discovery shows there are still an awful lot of things to uncover on this planet. It’s really exciting.”