for a few minutes after reaching the wreck, which had so occupied their thoughts for the past weeks, the adventurers did nothing but gaze at it from the ports of the submarine. the appearance of the deep-water sharks gave them no concern, for they did not imagine the ugly creatures would attack them. the treasure-seekers were more engrossed with the problem of getting out the gold.

"how are we going to get at it?" asked tom, as he looked at the high sides of the sunken ship, which towered well above the comparatively small advance.

"why, just go in and get it," suggested mr. damon. "where is gold in a cargo usually kept, captain weston? you ought to know, i should think. bless my pocketbook!"

"well, i should say that in this case the bullion would be kept in a safe in the captain's cabin," replied the sailor. "or, if not there, in some after part of the vessel, away from where the crew is quartered. but it is going to be quite a problem to get at it. we can't climb the sides of the wreck, and it will be impossible to lower her ladder over the side. however, i think we had better get into the diving suits and take a closer look. we can walk around her."

"that's my idea," put in mr. sharp. "but who will go, and who will stay with the ship?"

"i think tom and captain weston had better go," suggested mr. swift. "then, in case anything happens, mr. sharp, you and i will be on board to manage matters."

"you don't think anything will happen, do you, dad?" asked his son with a laugh, but it was not an easy one, for the lad was thinking of the shadowy forms of the ugly sharks.

"oh, no, but it's best to be prepared," answered his father.

the captain and the young inventor lost no time in donning the diving suits. they each took a heavy metal bar, pointed at one end, to use in assisting them to walk on the bed of the ocean, and as a protection in case the sharks might attack them. entering the diving chamber, they were shut in, and then water was admitted until the pressure was seen, by gauges, to be the same as that outside the submarine. then the sliding steel door was opened. at first tom and the captain could barely move, so great was the pressure of water on their bodies. they would have been crushed but for the protection afforded by the strong diving suits.

in a few minutes they became used to it, and stepped out on the floor of the ocean. they could not, of course, speak to each other, but tom looked through the glass eyes of his helmet at the captain, and the latter motioned for the lad to follow. the two divers could breathe perfectly, and by means of small, but powerful lights on the helmets, the way was lighted for them as they advanced.

slowly they approached the wreck, and began a circuit of her. they could see several places where the pressure of the water, and the strain of the storm in which she had foundered, had opened the plates of the ship, but in no case were the openings large enough to admit a person. captain weston put his steel bar in one crack, and tried to pry it farther open, but his strength was not equal to the task. he made some peculiar motions, but tom could not understand them.

they looked for some means by which they could mount to the decks of the boldero, but none was visible. it was like trying to scale a fifty-foot smooth steel wall. there was no place for a foothold. again the sailor made some peculiar motions, and the lad puzzled over them. they had gone nearly around the wreck now, and as yet had seen no way in which to get at the gold. as they passed around the bow, which was in a deep shadow from a great rock, they caught sight of the submarine lying a short distance away. light streamed from many bull's-eyes, and tom felt a sense of security as he looked at her, for it was lonesome enough in that great depth of water, unable to speak to his companion, who was a few feet in advance.

suddenly there was a swirling of the water, and tom was nearly thrown off his feet by the rush of some great body. a long, black shadow passed over his head, and an instant later he saw the form of a great shark launched at captain weston. the lad involuntarily cried in alarm, but the result was surprising. he was nearly deafened by his own voice, confined as the sound was in the helmet he wore. but the sailor, too, had felt the movement of the water, and turned just in time. he thrust upward with his pointed bar. but he missed the stroke, and tom, a moment later, saw the great fish turn over so that its mouth, which is far underneath its snout, could take in the queer shape which the shark evidently thought was a choice morsel. the big fish did actually get the helmet of captain weston inside its jaws, but probably it would have found it impossible to crush the strong steel. still it might have sprung the joints, and water would have entered, which would have been as fatal as though the sailor had been swallowed by the shark. tom realized this and, moving as fast as he could through the water, he came up behind the monster and drove his steel bar deep into it.

the sea was crimsoned with blood, and the savage creature, opening its mouth, let go of the captain. it turned on tom, who again harpooned it. then the fish darted off and began a wild flurry, for it was dying. the rush of water nearly threw tom off his feet, but he managed to make his way over to his friend, and assist him to rise. a confident look from the sailor showed the lad that captain weston was uninjured, though he must have been frightened. as the two turned to make their way back to the submarine, the waters about them seemed alive with the horrible monsters.

it needed but a glance to show what they were, sharks! scores of them, long, black ones, with their ugly, undershot mouths. they had been attracted by the blood of the one tom had killed, but there was not a meal for all of them off the dying creature, and the great fish might turn on the young inventor and his companion.

the two shrank closer toward the wreck. they might get under the prow of that and be safe. but even as they started to move, several of the sea wolves darted quickly at them. tom glanced at the captain. what could they do? strong as were the diving suits, a combined attack by the sharks, with their powerful jaws, would do untold damage.

at that moment there seemed some movement on board the submarine. tom could see his father looking from the conning tower, and the aged inventor seemed to be making some motions. then tom understood. mr. swift was directing his son and captain weston to crouch down. the lad did so, pulling the sailor after him. then tom saw the bow electric gun run out, and aimed at the mass of sharks, most of whom were congregated about the dead one. into the midst of the monsters was fired a number of small projectiles, which could be used in the electric cannon in place of the solid shot. once more the waters were red with blood, and those sharks which were not killed swirled off. tom and captain weston were saved. they were soon inside the submarine again, telling their thrilling story.

"it's lucky you saw us, dad," remarked the lad, blushing at the praise mr. damon bestowed on him for killing the monster which had attacked the captain.

"oh, i was on the lookout," said the inventor. "but what about getting into the wreck?"

"i think the only way we can do it will be to ram a hole in her side," said captain weston. "that was what i tried to tell tom by motions, but he didn't seem to understand me."

"no," replied the lad, who was still a little nervous from his recent experience. "i thought you meant for us to turn it over, bottom side up," and he laughed.

"bless my gizzard! just like a shark," commented mr. damon.

"please don't mention them," begged tom. "i hope we don't see any more of them."

"oh, i fancy they have been driven far enough away from this neighborhood now," commented the captain. "but now about the wreck. we may be able to approach it from above. suppose we try to lower the submarine on it? that will save ripping it open."

this was tried a little later, but would not work. there were strong currents sweeping over the top of the boldero, caused by a submerged reef near which she had settled. it was a delicate task to sink the submarine on her decks, and with the deep waters swirling about was found to be impossible, even with the use of the electric plates and the auxiliary screws. once more the advance settled to the ocean bed, near the wreck.

"well, what's to be done?" asked tom, as he looked at the high steel sides.

"ram her, tear a hole, and then use dynamite," decided captain weston promptly. "you have some explosive, haven't you, mr. swift?"

"oh, yes. i came prepared for emergencies."

"then we'll blow up the wreck and get at the gold."