The boys went back to the water and gazed at it. Jack saw that through hundreds of years the waterfall had worn itself a bed or channel on the floor of the cave, and that only the surface water overflowed on to the ground where the boys stood. The channel took the main water, and it rushed off down a tunnel, and then was lost to sight in the darkness.
“I suppose the robbers couldn’t possibly have gone down that tunnel, could they?” said Paul suddenly. “There isn’t a ledge or anything they could walk on, is there, going beside that heaving water?”
The boys tried to see through the spray that was flung up by the falling water. Jack gave a shout.
“Yes — there is a ledge, and I believe we could get on to it. For goodness’ sake be careful not to fall into that churning water! We’d be carried away and drowned if so, it’s going at such a pace!”
The boy bent down, ran through the flying spray, and leapt on to a wet ledge beside the water, just inside the tunnel into which it disappeared. He nearly slipped and fell, but managed to right himself.
He flashed his torch into the tunnel and saw the amazing sight of the heaving, rushing water tearing away down the dark vault of the mountain tunnel. It was very weird, and the noise inside the tunnel was frightening.
Paul and Mike were soon beside Jack. He shouted into their ears. “We’d better go along here and see if it leads anywhere. I think this is the way the robbers must have gone with Ranni and Pilescu. Keep as far from the water as you can and don’t slip, whatever you do!”
The boys made their way with difficulty along the water-splashed tunnel. The water roared beside them in its hollowed-out channel. The noise was thunderous. Their feet were soon wet with the splashing of the strange river.
“The tunnel is widening out here,” shouted back Jack, after about an hour. “Our ledge is becoming almost a platform!”
So it was. After another minute or two the boys found themselves standing on such a broad ledge that when they crouched against the back of it, the spray from the river no longer reached them.