The submarine craft was caught in the cave under the ocean, and there seemed no way of escape.
The darkness outside was intense, and the water still boiled and foamed upon every side.
Once a huge rock came squarely down upon the upper side of the new Holland with a shock that made those inside fear the craft would be smashed flat.
But at last all became quiet as a tomb.
The searchlight was brought into play and they looked eagerly for some way out of the cave.
But rear and front entrances were blocked by rocks almost as large as the Holland herself and could not be budged.
An hour passed—a time full of awful anxiety.
What if the whole top of the sea-cave should give way?
It would prove the end of the new Holland and all on board!
"We must do something," said Oscar. "I am going outside.