Percival took as much room as he could in the narrow passage, swung the
axe, and sent the door crashing into the space beyond.

Instead of a flood of water breaking in upon the boys, as Jack more than
half expected, there was considerably more light while the sound of water
was more distinguishable than before.

"Well! I declare!" exclaimed Percival, pressing forward.

The boys found themselves in the after cabin of a vessel, which was as dry
as if she had been in her dock, a soft light from overhead showing them
the details of the place perfectly, even without the light of the torch.

"We are under water, Jack!" cried Percival.

"So it seems."

"That light comes from the bull's-eye overhead. The water over it softens
the light. Otherwise, the sun would pour right into the place."

"That would be better than having the water pouring in on us, Dick. The
flashings of that skylight are tighter than most of them, however, or the
water would have gotten in here long before now."

"It is just possible that the glass has been covered with sand which has
been lately washed away. That would fill all the cracks around the
flashings and make them tight. Very likely the wave that sent us in here
has uncovered the skylight, and that is how it is light in here. It is
dry, too, Jack. Why, this is like being in one of the submarines we have