The water swarmed with fish, but they were like none that the adventurers had ever seen or dreamed of before. There were monsters with hideous heads, and eyes so large that they occupied nearly half of the ugly bodies. Then there were serpent-like forms, fish with long slender bodies and whip-fashioned tails, with jaws that extended before them for ten feet or more. Others there were, great lumbering monsters that crawled along on the ice, somewhat as seals do. After several hours' travel the submarine ran into a school of fish that had shapes like those of polar bears, while their heads were like those of sharks. The creatures swarmed up to the side of the vessel, and some scratched with their claw-like fins on the glass windows of the conning tower and the side bull's-eyes. A meal was prepared by Washington, and all the adventurers brought good appetites to the table. On and on rushed the ship, every hour coming nearer and nearer to the pole. Professor Henderson had turned the steering of the craft over to Mark, who, with Jack as an assistant was sending her along at a good speed, when suddenly the submarine seemed to slacken in her progress. "What's the matter now I wonder?" asked Mark. "Maybe the engine bearings got hot, and Washington had to slow up to cool them," suggested Jack. He looked through one of the side windows in the conning tower, a moment later, and uttered a cry of fear. "What is it?" asked Mark. Jack pointed with a hand that trembled from fright. Staring at them through the thick glass of the bull's-eye the boys beheld the most hideous sea monster they had yet encountered. It seemed to be a vast circular mass of flesh, twenty feet in diameter, and, in the middle were two openings each three feet across. They were like big holes, and, at the farther end of them could be seen two unblinking eyes. In the centre was a horrible mouth, armed with a triple row of teeth. Down below there was a short body, at the end of which was a smaller disk, armed with a sharp horny point. "What is it?" asked Jack in a whisper. "I don't know," replied Mark. A moment later Mr. Henderson came up the companionway into the tower. He caught one glimpse of the monster. "It is the great sucker of the polar seas!" he exclaimed. "Quick! Speed up the engine! If that one, and the mates of it, fasten on to us we will have trouble!" He pressed the signal that connected with the engine room, and told Washington to start the engine at its greatest power. The next instant the ship throbbed and trembled under the vibrations of the big screw. "We may escape!" cried the professor. As he spoke the ship seemed to come to a sudden stop. The engine could still be felt moving, and the big screw still churned the water to foam in the tunnel, but the craft was stationary. "We are caught!" exclaimed the professor. "So we are!"