Full-face masks, climbing and diving: How Thai boys are being rescued from narrow cave

Eight boys and their football coach remain trapped in a flooded Tham Luang cave complex in Chiang Rai, Thailand, as operations to rescue them enter their second day (July 9).

Four of the twelve boys were rescued on Sunday (July 8), with authorities declaring the mission -- touted as a 'race against time and water' -- as being more successful than hoped.

The rescue operation was paused overnight so that oxygen tanks could be replenished and will continue with the same group of 18 international and Thai Navy Seal divers.

A worker prepares oxygen tanks during rescue operations to save 12 boys and their coach trapped inside Tham Luang cave on July 8, 2018. (Photo: EPA-EFE)

It wil take two to three days to safely free all the boys and their coach, who have been stranded since July 23.

The monsoon season, strong water currents, the cave's layout and the boys' inability to dive were previously cited as reasons for why the rescue mission would be fraught with peril.

While experts and officials had debated on the safety way to evacuate the group, with various rescue methods being considered, they eventually settled on the "swim and dive" option.

This involved getting the boys to swim and dive through a complex network of narrow, muddy, submerged passageways inside the cave.

Authorities decided on which boys to rescue first based on their health, said Mr Narongsak Osotthanakorn, head of the rescue operation.

Mr Narongsak Osatanakorn speaks at a press conference near Tham Luang cave on July 8. (Photo: The Straits Times, Jitsiree Thongnoi)

According to Mr Narongsak, the boys rescued were underwater for around one-fifth of the 5km escape route from a high ledge where they had sought refuge to the cave's mouth.

"The boys were wearing full-face masks and were able to breath normally during the operation," he added.

Each boy was accompanied by two divers through the cave, with the narrowest stretch requiring divers to remove their scuba gear in order to pass through.

The boys also had to do a mixture of walking, wading, climbing and diving in low visibility along guide ropes already put in place by rescuers, reported The Straits Times.

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"The biggest crisis spot for diving is on the left from the T-Junction,” added Mr Narongsak.

"There is a tunnel that has a passageway going up and coming down narrowly and you have to turn a bit and it’s very small."

After that though, the tunnels widen, the waters subside, and walking is even possible, said Thai authorities.

Upon exiting the cave, the rescued boys were transported by ambulance to the helicopter within two minutes.

Their family members will not be allowed to visit them during the first 24 hours as they undergo physical examinations.

Family visits will be allowed only after their medical check-ups are completed in 48 hours.

The rescue team will be performing an assessment of Sunday's operation in order to get ready for the next rescue mission, said Mr Narongsak.