I love this kind of thing because I like reading and picking out the relevant information... its ALL there.. floodwaters, dangerous cave, rainy season, trying to pump out the flood water but really not making headway... And there you have your answer.. the boys went in encountered flood water and probably limited air.. . The simplest and most obvious explanation is usually the right one.. .conspiracy stories and monsters are just make belief.
Writing as one who has been caving for over 40 years, though never in tropical river-caves:
There are animals that live permanently in caves, and others that use them as roosts; but "monsters" - NO.
That group in Thailand have now been found, all alive thankfully, after tremendous efforts by Thai navy divers and others including two Britons I assume are experienced cave-divers (I've not heard their names on the News - I not very likely to know them personally but may well know their names from the literature).
They were trapped by flood-water, as simple as that, but luckily were in or able to retreat to a higher-level series above the flood. It has happened to me, though for only one night and we were able to exit the cave easily in the morning; and it's not a pleasant experience even for that short time.
Pumping will only work if it diverts the main stream feeding the cave, safely away from its sink. (I have seen this done but on a far smaller scale than in this incident). Pumping water from the entrance series of a cave carrying a river fed from elsewhere, especially if a large catchment area absorbing heavy rainfall, is not usually likely to achieve anything until the rain stops and it can help drain low points still holding water.
So ignore any rhubarb about conspiracies and monsters. "Dangerous" cave though? I'm not sure how you'd define that - by the risk of flooding perhaps, which is obviously greater in the rainy season.
