“Here is another door, Jack,” said Percival.  “I don’t see any sign of a companionway from the deck.”

“No,” said Jack, putting his ear to the door and listening intently.  “I can hear the swash of water just the same, Dick.  We had better be a bit careful.”

“We would hear it here, anyhow, Jack.  There is water outside, and I don’t suppose there is much depth here.  You would be very likely to hear it the same as you hear water dashing against the side of a vessel when you are in the hold.  It doesn’t follow that the water is beyond there.”

“No, I guess not.  Well, give it a smash, and be ready to run in case there is water there.”

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 read of.”

“Where you slide back a panel and look at the fishes in procession, through a plate-glass port,” laughed Jack.  “That always seemed absurd to me, but there are lots of things that Verne wrote about which have been more than realized.”

“I should say so!  Why, his balloons and his submersibles would not be a patch upon what are actually in use these days.”

“Well, now that we know it is safe here, and the water is not going to pour in upon us, let us have a look at the place,” said Jack.

CHAPTER VII

A REMARKABLE FIND

The cabin where the boys now found themselves, so strangely lighted and so marvelously discovered, was not of any great size and was evidently the stateroom of the late commander of the vessel, which itself was not of any great size so far as the boys could determine.