The ocean heaved, and our ships seemed small in the face of the storms. It didnt matter, we had a job, a duty to do. The kings of the oceans liked to come into the shallows where they destroyed the shoals of fish that we survived on. The monsters can crack the hulls of smaller ships, and many a sailor has lost his life in their massive jaws. There is a spray ahead, one of the emperor whales has come to the surface, we take up our spears and harpoons, let us try our steel and luck against the leviathans of the deep.
The Jaws of the Deep
The largest predators of the ocean are not sharks, though they are more well known. The largest predators seldom venture into the shallow waters where men send their trawlers and fishing ships. Only the merchant ships that venture into the deep ocean run the risk of encountering these whales. Banish from your mind the image of the baleen whale breaching from the water, blowing spumes of water into the air. These whales are sixty to eighty feet in length, their bodies are long and muscular, with a powerful fluke and strong pectoral fins. The head is the part of their body that is the most frightening and dissimilar from common terrestrial whale. The jaws are large and robust, with teeth the size of small lances. The Emperor Whale is a predator that hunts giant squid, sharks, other whales, and any other creature foolish enough to venture into their waters.
The beast rose from the water, its jaws opened, water streaming from its massive teeth. we acted, our spears and harpoons flew, most vanished into the roil of the ocean. Others struck home, and the water was stained red with the blood of the beast. It wasnt going without a fight, and it struck the lead ship, the Sea Sparrow, across the bow. Wood splintered and several men fell into the water. They fought the surge but in vain. the beast saw them, heard their struggles. They vanished, snap snap snap, into the jaws of the deep. More spears came from the other ships, lines tied to them.
The Emperor Whale is hardly an endangered species. A massive predator of the ocean, the whale is a threat to sailing ships and other vessels that would ply those waters. They are drawn to the passage of the ship, or the trail of debris they leave in their wake. The Emperor Whale is also an avatar of the oceans. In the real world, nature is something that needs to be protected, in the dark fantastic, the opposite is true. The Emperor Whale hunts ships, rather than the other way around. The ships that are involved in whaling ply a dangerous task, hunting a beast easily as dangerous as a dragon, but out in the open sea.
The Emperor Whale is intelligent, they are protective of their domains and they are well aware that the presence of the fishing ships impacts their feeding grounds. The equation is simple, the more (boats) there are, the less food there is. Eat the (boats) and then there will be more food to eat.
The beast was played out, he was bleeding from a dozen true harpoon strikes, and the water was a froth of foam and his damned blood. Of our three ships the Pjizen was probably half way to the bottom. The Faleste was badly damaged and if the sea was willing might make it back to port. The men worked the tow lines and the winches and we drug that big bastard up onto the rear deck. He was so big that we could only get his front half up. That was fine. Men with stronger stomachs than I went to their work with those big whale axes, the blades chopping into his tough skin, and the thick meat under it. His jaws worked a few times, those eyes rolling in his his head even after they finally loped it off. The holds were filled with meat, and more importantly, all the whale fat they could hold. It was not a great day, but, with more than half of the men we set out with surviving, it was not a bad day either.
Have Axe, Will Travel - Whaling is dangerous business, ever moreso with a large, intelligence and highy aggressive beast like the Emperor Whale, the PCs are hired to work on a whaling ship and after working sails, rope work, and other aspects of being a sailor, they get to fight toe to toe with a gargantuan foe without the benefit of dry land, cavalry, or any of those other advantages they are likely used to.
Emissary of the Deep - Is he a madman, or is he truly an emissary? A sailor appears, he has been missing for weeks, or even months. He tells a wild tale of being swallowed whole by an emperor whale. Rather than being digested, he was given a chance to serve the Great Whale. Rather than end up whale poop, the sailor agreed. He brings messages that certain areas of the ocean belong to this particular whale, and that they are tresspassing and it will not be tolerated. No one believes the sailor, until the first small ship in the harbor is taken, its hull crushed and its crew found in floating pieces.
Side Note: Conservation and preservation are the watchwords of our current era. In this fantastic setting, neither of these words are considered. Between intelligence megafauna such as the Emperor Whale, exotic flora such as treefolk and dryads, and the presence of elementals whose sole purpose is maintaining the balance of the ecosystem mankind must strive against nature, rather than protect it.