a kilometer or a quarter of this cave remains completely submerged. that s equal to 11 football fields. wow. that these kids who have never been in a scuba mask, would have had to go under and get out and is worked. so here s the question. if that worked, why did they stop? you mentioned it earlier. they simply used up all their oxygen doing this. they have to recharge. that could take from 9 to 20 hours, according to officials, and yes, they are racing the clock. this is all the water they have been pumping out, the stuff that s already fallen. they have had a little lull. and you saw a minute ago as the rain was returning, that s the forecast. they have to work fast, even in this incredibly dangerous work, if they want this to be fully successful. dana? such important context and explanation of what s going on down there. tom foreman, thank you so much. with us now for more is an experienced diver who has taken part in other rescue missions, rick murkar, president of the nation
hour. the strategy is to teach the boys how to scukubcuba dive, so can make their way out of the cave. that is the challenge. what the rescuers have faced, dave. any sense of a time line how long we could be waiting? reporter: look. i mean, it could be weeks. it could be months. just really depends. we know that some of these boys can t swim. so, this cave system, it s huge. it s 10 kilometers long. it s like a labyrinth. some of these areas, some of these chambers are flooded. so, these boys are going to have to learn to breathe through a scuba mask. if anybody has learned how to scuba dive, it can be daunting. certainly in water, let alone in a cave that is narrow. they have to crawl through