"Large Marge, the Scourge of the Deep!"
Large Marge is a massive creature that has been terrorizing the citizens of the Aleutian islands. Villagers describe her to be a massive mutated whale, that runs ships aground and swallows rowboats whole. She has even sunk the great Bastaršur, a ship that has brought supplies from the south for years. Rumor has it, that the Bastaršur has great treasures of gold and thermanium, and Large Marge wishes to keep them for herself. Everyone has feared the massive beast, except for Captain Baha, an immigrant from Jamaica, has dedicated his life to catching Large Marge, and he needs your help.
And my tacos are done, cool
And the quest ends when all the crew are dead at Marge's hands, Marge is dead, and you're sailing through the ocean, telling the nearest ship about Large Marge's death, and you get some of the treasure.
Too much like Moby Dick?