It seemed to Ned that the first thing for him to do was to locate the submarine. For all he knew, prowlers from her might be nosing around the Sea Lion.
He had left the door to the water chamber open, of course, and so it must remain until he returned. Jimmie, owing to a defect afterwards corrected, could not expel the water while the door was open, nor could he close the door from the interior.
Fearful that some mischief was on foot, he grasped Jack by the arm and hastened back to where Frank had been left. His first care should be to find the exact location of the hostile submarine and then see that no air-hose reached from her to the Sea Lion.
The three boys passed out of the wreck and came to the stern of the once fine ship. She had gone down prow first, and the stern was a little above the level sand floor of the sea.
Instead of passing around the stern and coming out on the other side, the boys halted and crouched down, so as to see under the keel. As the outer shell of the ship was here at least a yard above the bottom, it was plain that the cargo had swept forward when she went down, thus holding her by the nose.
There was no longer any doubt as to what was going on. There, only a few yards away, lay the dark bulk of a submarine. Only for a light glimmering through the closed door of the water chamber it could not have been seen at all.
The men who were working in the wreck had taken no chances in leaving the boat. Their lines and air-hose passed through the outer door in well-guarded openings, and the interior was as safe from intrusion as a walled-in fortress.
Ned regretted that he had not observed the same precaution in leaving the Sea Lion, still he did not believe that his boat had been attacked. After a few moments devoted to observation, Ned crept around the keel and looked down the side of the ship which lay toward the submarine. Men with electric lamps in their helmets were working there.
They appeared to be forcing an entrance into the lower hold of the ship through a small break in the shell. This led him to the conclusion that the way to the very bottom was blocked from the inside, and that the gold—if it had been stored there—had not yet been removed.
He returned to his chums and all three started back to the Sea Lion. The men about the wreck were all so busy that it did not seem to Ned that they knew of the presence there of his submarine.