A lack of oxygen is as deadly a threat as the imminent monsoon rains, which could further flood the caves.
The question is, can rescuers keep them alive long enough to save them.
The monsoon rains grow ever closer but a rescue attempt that's already proved deadly remains frustratingly far away.
The local Governor says the boys are not ready, and so they wait in the dark below.
"No, not today because the boys are not suitable - they cannot dive at this time."
Oxygen levels in Tham Luang cave pose the latest grave concern.
If the 12 boys and their coach stay where they are, they risk either running out of air or drowning. But the only way out - to dive through the labyrinth - is fraught with danger too.
Former Thai Navy SEAL Saman Gunan lost his life in the plight to save theirs. While re-supplying air tanks along the escape route, he lost consciousness underwater and died. Filming himself just days earlier, before he embarked on his volunteer mission, he said "we will get those kids home".
His sacrifice makes him a national hero and he will receive one of Thailand's highest honours - a funeral sponsored by the Royal family. His colleagues vow his death will not be in vain.
Rear Admiral Arpakorn Yookongkaew, Commander Royal Thai Navy Seals, says time is up for the rescue and they must act now.
"We can no longer wait for all the conditions to be right because circumstances are pressuring us. We originally thought the boys could stay safe inside the cave for quite some time, but circumstances have changed. We have a limited amount of time."
Thai government diver Songkran Yodpunkham says they have no other option and should be taking them out by diving.
"This could make them panic or cause them to choke and that would use up a lot of air. It could be terrible - they could start hyperventilating. It's also zero visibility."
Eighteen shafts have been drilled from above, but so far none has reached the chamber, while other teams scour the dense Thai jungle for possible holes to the caverns below.
Newshub.
