|Part of the river found in the world’s biggest cave Son Doong (Photo: Ryan Deboodt)
Nguyen Chau A, the organiser, said the mission would start next month in an attempt to find out whether an underwater passage links Son Doong with Thung Cave.
He said if they were right, it would mean Son Doong was even larger than previously thought because the two caves would be classed as one.
According to Oxalis Adventure Tours, British caver Howard Limbert would be technical director on the mission, accompanied by Rick Stanton, John Volanthen, Jason Mallison and Chris Jewell.
The four are described as the world’s best cave divers and played a key role in rescuing the young footballers in July last year.
Limbert, who is a member of the British Cave Research Association, said he and his team had suspected the existence of the passage during a survey of Son Doong in 2010 as the end of an underground river went in a straight line from the end of Thung Cave.
Thung Cave is about 600m from Son Doong. Water levels in the passage are about 40m deep. Thung Cave was first explored in 1994 and has a large river running through it, just like Son Doong.
Limbert said he believed the current inside the passage would be strong due to the large volume of water from the river pouring into a narrower passage and said the mission would be tough.
The team of four British divers will joined by caving expert Martin Holroyd, who works as a safety guide for Oxalis.
Oxalis Adventure Tours is the sole tour provider to the world’s biggest cave.
Oxalis sponsored a total of 53,000 USD for the mission and is working with the Phong Nha-Ke Bang National Park as the organiser.
The company is looking for assistance from international media partners to report on the mission.