The monsoon lasts until the end of summer. But the floodwaters cut off their path of escape.
None of the boys know how to swim.
If diving proves impossible, there is an outside chance a hole can be drilled into the cave to evacuate them or they will have to wait for waters to recede and walk out - the longest of the options. Many people are coming.
There is no simple way to save the trapped team.
Reymenants said the easiest option would be to "keep pumping the water out of the cave". But if the dives are hard then "supply will be hard, but the risk of trying to dive them out is also exponentially greater".
"'Time is not on our side - we're expecting heavy rain in three days", he told BBC Newsnight on Monday.
It is believed they entered the cave on 23 June when it was dry and sudden heavy rains blocked the exit. It is estimated that the boys are around half a mile below the surface.
"How many of you?" the diver can be heard as saying.
The boys showed glimpses of smiles throughout the brief video, which was recorded sometime Tuesday and posted to Facebook on Wednesday.
Capt. Akanand Surawan with the Royal Thai Navy said that the team had been given four months' worth of food, and the boys are reportedly being taught how to dive. "Monday. You have been here - 10 days".
"The water is very strong and space is narrow". "If it's risky or not safe, we will not proceed yet", Narongsak said.
Night's sister said her brother and the three boys from the same village would gather at their house almost every day before going out to play.
Experts have cautioned that any attempt to traverse the confined passages will be fraught with difficulties and potential complications, especially if the children can't swim.
Members of the British cave-diving community say that Stanton and Volanthen have been involved in a number of high-profile rescues.
The council had sent its divers on the request of Thai authorities. "Those are more manageable and they don't affect the group as a whole, in general", Mirza said. "Panic and adrenaline are great in certain situations - but not in cave diving", he said. Thank you so much. They appeared to be in good spirits, occasionally laughing.
"There are a few ideas to rescue them, some of them are longer and some are shorter".
He said it was unknown when an extraction could be attempted, but it was unlikely to be today.
The natural chimney, around 1.5 meters in diameter and at least 22 meters (72 feet) deep, was found to the north of the opening of the cave, where the boys' bikes were found last Saturday.
The authorities were keen to get the boys out as soon as possible, but not if it was unsafe.
Chiang Rai Governor Narongsak Osottanakorn said the authorities were keen to get the boys out and suggested it might have to happen in phases, but only when safe.
Khaosod English, a Bangkok-based news organization, reported that officials are calling for donations of small diving masks that would fit the boys, as regular diving equipment could be too risky. Officials said on Tuesday that the boys, aged 11-16, and their 25-year-old coach were mostly in stable medical condition and have received high-protein liquid food.
"My biggest fear is that they would decide, 'OK, we're going to leave them in there until the rainy season is over in a place where there are hunkered down, '" Dally said.
"After that many days, their normal circadian rhythm would start to break down", said Frappier, the scientist. This would see the 13 people be kitted up with weights and other equipment which would allow the divers to drag them out of the cave. They clearly want to stabilize the boys before they try and bring them out.