Cthulhu, aquatic horror, underwater lair, dark abyss, eerie bioluminescent lighting, twisted coral reef, ancient ruins, seaweed-covered pillars, mysterious artifacts, glowing orbs, Cthulhu's massive tentacles, eerie eyes, sharp teeth, scaly skin, powerful claws, worshippers in diving suits, ritualistic chanting, dimly lit underwater chamber, foreboding atmosphere, dark magic, Lovecraftian horror.