"Everyone down below," he said. "We're going to submerge and run underwater to the Sea King plant. That may throw Sladek's ship off our trail." They tumbled below, the main hatch was sealed, and Pat checked every gauge before Commander Ford gave the order to submerge. The _S-18_ went down twenty feet and then levelled off, the electric motors pushing it smoothly underwater. With his eyes glued to a periscope, Commander Ford scanned the surface of the sound for another craft. At almost an instant's notice the _S-18_ was ready to dive lower. At the microphones, Ike Green was listening intently for the beat of the propeller of the tramp steamer. He grinned as Commander Ford entered the tiny room. "They're puzzled," said the radio man, "and they're zig-zagging all over the lower bay." The _S-18_ continued to run underwater at a bare four knots an hour. It was three hours later when they came to the surface and the sky was lighter in the east. Sunrise was less than half an hour away. To their left was the factory of the Sea King company and the _S-18_ nosed slowly toward the dock. As the sky brightened they saw the smudge of a steamer well out to sea. "Unless I miss my guess there goes Jack Sladek and his treasure-hunting expedition," grinned Pat. The seaplane purchased for their trip was on the dock ready and it took less than half an hour to load the craft on the deck of the _S-18_ and make it fast. "There'll be no more diving with that sky-hopping bug on deck," said Pat. "Which will suit me all right," replied Tim. "Anytime you want to do a little exploring under water in this tin fish just let me know and I'll cruise around in the clouds for a couple of hours." "You may have to do that when we get down into the Caribbean if we find Sladek too close to our trail," put in Commander Ford who had come up behind them. "He's going to be a hard customer to lose and he'll probably use that seaplane of his to do a lot of scouting." Breakfast was served by Al Hardy, who was the cook, and they enjoyed the morning meal before casting loose from the Sea King dock. Then, with all hands on deck and a bright sun shining down on them, the _S-18_ resumed its southward voyage. The next port of call was to be Key West, where the fuel tanks would be replenished for the voyage across the Caribbean. Once out to sea, half of the crew turned in, for there had been no sleep aboard the _S-18_ during the hours they had been submerged. The Jersey coast gradually dropped from view and they moved southward at a steady ten knots an hour. Tim sought his bunk in the after quarters. Ahead the Diesels pounded steadily, but the air was clean and sweet and in spite of the noise he was soon asleep. The clatter of pans as Al Hardy prepared the noon meal awoke him and he rejoined Pat in the conning tower. Commander Ford was down in the diving room talking with the chief divers and Tim and Pat were alone.