"I must get out! I simply must!"
The cry was an inspiration, for, getting on his knees, he felt around and found that two of the big rocks were unsteady upon their resting places.
He pulled away at the smaller stones beneath, and soon had them loosened.
He continued his labors, and presently, with a mighty crash, one of the rocks slid down into the stream, disappearing beneath the surface with a splash.
At once the light from beyond shot into the opening. He was free!
His heart gave a bound of joy, and quickly he scrambled through the hole and into the cave beyond.
This was a large affair, being at least forty feet wide and high, and several hundred feet long.
"Now, if only Bob were safe, all would be well," thought the young diver.
Without waiting to light another torch he began to move toward the outer opening of the cave.
But before he had gone half the distance he came to a halt with a cry of dismay.