Headcam footage reveals the dark and waterlogged tunnels the Thai boys trapped 800m underground will have to pass through to escape.
Rescue workers trying to save the 12 schoolboys, who have been trapped inside the Thai cave for 13 days, are seen wading up to their necks in fast-flowing, murky water.
The video shows them making their way through the cave’s claustrophobic labyrinth of chambers while desperately clinging on to a rope.
Navigating through the cave system to where the football team is holed up takes experienced divers more than five hours in the flooded conditions.
The rescue workers use head torches to slowly progress through rocky, dimly-lit passages – but they can only get so far before full diving equipment is required.
At this time, the only way for the schoolboys to escape the cave is by diving – but none of them have experience and only a few of them can swim.
It’s not all gloomy, however, as the rescuers pass the time by cracking jokes and laughing with each other before taking the plunge underwater.
The divers carry equipment or food for the trapped team enclosed in plastic bags, holding them above their heads for as long as they can before submerging.
Most of the divers are Thai or from surrounding Southeastern Asian countries but a few Australians and Europeans are heard doing a headcount.
Divers must squeeze through rocky tunnels at some points less than a metre wide or high – too narrow for them to wear oxygen canisters on their backs.
They will instead have to pass them through the openings first then swim through while another diver holds them on the other side.
The boys, aged 11-16, and their 25-year-old coach went exploring in the cave after a football game on June 23.
They became trapped after rain flooded the Tham Luang caves near Mae Sai and were not found for more than a week.
Officials have long feared the coming torrential rain would catastrophically flood the cave system in Chiang Rai and make rescue impossible.
Should the rains further flood the cave, as predicted, the team could be trapped in the cave for more than four months until waters recede.
Rescuers may therefore be forced to try a rescue imminently despite the boys and their coach not having regained their strength.
They also can’t swim and have zero diving experience, making a rescue very dangerous.