Approximately 40 years ago, Nathaniel Omen realized he couldn't rule the world. But what was to stop him from ruling 3/4 of it? He built the Infra-World, and outfitted it with a large group of people with similar desires. At the bottom of the ocean, Captain Omen's men began to lay claim to the ocean floor, stopping only as it approached the borders of other nations. Over the years, the Infra-Worlders learned to control the dreaded Toad-Whales. Omen had a son by an unnamed woman, whom he named Filius. He also created Aquon to be his secret weapon, in case of attack, mutiny, or what-not.
Captain Omen and the Infra-Worlders observed a submarine on the far end of the losing side of a struggle with the Hulk. Omen had the Hulk and the sub brought aboard the Infra-World. The Hulk was merely annoyed with being on the Infra-World, until he learned that Captain Omen would want him to do his work. The Hulk busted out of the sub, got a bad case of the bends trying to swim up to the surface, and had to be rescued by the Infra-Worlders and those dreaded Toad-Whales. In the process of being decompressed, the Hulk turned back to Banner, and everything was fine for awhile. Then the Hulk couldn't just swim back to the surface,so he stood on the ocean floor and tried to figure out a plan. Captain Omen was nice enough to send out an oxygen helmet to let him live but then told him that he would have to wander the ocean floor, follow the Infra-World, and obey him, or else he would pump his helmet full of poison gas.
Fortunately for the Hulk, many of the Infra-Worlders were rebelling against Captain Omen, so they helped him back into the ship, in turn. Captain Omen was furious when he learned of the mutiny and released Aquon, his secret weapon, to route his opposition. The Hulk fought Aquon, shattering the hull of the Infra-World in the process. Omen had the ship repair itself and pump out the water, but Aquon got sucked outside in the process. Captain Omen was forced to concede to the Infra-Worlders and bring them to the surface world, where they began to very rapidly die off. He quickly re-pressurized the ship and saved the others still on board, but he left everyone else outside to perish—including his son, Filius. Captain Omen took the Infra-World back to the ocean floor.
Captain Barracuda was later shown occupying a base that Omen had once used and abandoned. No further explanation was given.