There was little they could do to protect themselves. They would either escape or be blown to pieces in case the explosive exerted too great a force. They all put on life preservers to guard against the contingency of the _Porpoise_ being ripped apart and themselves cast into the water, yet they realized that without their ship, they could live but a little while in the ice-filled water near the south pole. The professor saw that everything was in readiness. He hesitated a moment and looked at the electric button in his hand, for this time the dynamite was to be detonated by a battery. How much might depend on one push of the finger! There was a slight movement to the muscles of the professor's hand. Then it seemed as if a thunderbolt had fallen into the midst of the ocean about them. There was a dull rumble, but the confined space and the thick walls of the ship shut most of it out. It was followed by a sickening dizzy motion to the submarine. She seemed about to roll over and those in her grabbed frantically at the sides. The next instant the craft plunged down, down, down, into the water which was filled with broken cakes of ice, that rattled against the steel sides, like peas in a pan. Down and down the _Porpoise_ went, for her tanks were full. More and more rapidly she continued to sink, until it seemed she would fetch up in the deepest cavern of the ocean. "We's gwine t' Mars Davy Jones's locker, suah!" Washington exclaimed as he looked at the depth gages. [Illustration: THEY WERE IN THE MIDST OF A GRAVEYARD OF WRECKED SHIPS.--_Page 200._] "Has the experiment succeeded?" asked Andy of Mr. Henderson. "I think so," was the answer. "At any rate we are free from the ice, temporarily at least. We are sinking down through the hole the dynamite made, just as I hoped we would." "Where will we end up?" asked Jack. "No one knows," replied the captain. "But I would say--" At that instant the ship stopped sinking and brought up with a bump. "I should say we were at the end of this part of our journey," finished the inventor. He turned off the cabin lights and lighted the search lamps that threw a gleam so the water could be looked at from the bull's-eyes windows. The sight that met their gaze was an astonishing one. They were in the midst of a graveyard of wrecked ships, and, on every side, scattered over the ocean bed, were the broken hulks that had once been stately vessels. CHAPTER XXV CAUGHT BY SEA SUCKERS "What sort of a place is this?" asked Andy, as he gazed at the last resting spot of the big ships. "They have probably drifted here with the ocean currents, become caught in the ice and have remained here hundreds of years," said Mr. Henderson. "Some of the ships are very old, and, by their build must have sailed the waters centuries ago." "Maybe some of them are treasure ships," suggested Jack. "They might be," admitted the professor. "Then we'll go aboard and get the gold," spoke Mark.