Oxygen tanks?
Are they using rebreathers or does the author not SCUBA knowledgeable?
SE Asia is filled with caves. I’ve been to many in Laos where you can walk back and around for at least 1/2 mile. I wouldn’t be hard to get lost or the group separated if they were in one that went further. There are holes where a misstep could be disastrous. In other words, they can be very dangerous. And possible they found one where they got lost. This one is close to the Mekong, so add water to that and it becomes extremely dangerous.
“Oxygen tanks?
Are they using rebreathers or does the author not SCUBA knowledgeable?”
Huh?