I wonder how far below ground they are? From what I've seen on you tube, two Asians with sharp sticks can dig just about anything anyone could ask for.
It seems to me you don't have to bore a rescue shaft, just a drain shaft from a lower elevation, and a safe distance from the boys, to get the water out.
Where is Tony Stark when you need him to build a boy size underwater transport pod for divers to guide in and out of a cave pronto?