The divers have rigged guide ropes through the passages of murky water and placed air tanks along the route. There is only one way out. And there is no hurry. The trapped can be supplied with all the food, medicine, lighting and communications they might need.
Their only need that cannot be supplied from outside is mental resilience.
The expert rescue divers now with them will be doing their utmost to make the boys relaxed at the idea of a long journey under water. If this is a typical bunch of early teens, some will be keen to have a go, others definitely not.
Those who are not confident in water will be battling terror. The keen ones will probably be given plenty of practice, because they will need it and because watching them should lessen the fears of the rest.
They were a team when they went into the cave system and they are probably a closer team now. For nearly 10 days they huddled together in darkness and silence deep underground.
They lost track of time, no doubt sleeping fitfully, drinking water dripping from the roof of the cavern, growing ever more hungry and constantly worrying they might not get out.
Compared with that worry, the ordeal they now face must seem manageable. For their families, the relief that their sons have been found alive appears to eclipse any worry about how the boys will get out.
Only the rescuers know how hard it will be to see that the boys do not panic when they find themselves squeezing through narrow confines where the water flow is overwhelming.
Will they all come through? They have done so well together so far.
The world is united in hope that their adventure will have a happy ending.