Submariner — Ocean Map

Hidden beneath the ice-choked waters of the Southern Ocean, the Abyssal Thalassa Caverns are a colossal network of submerged chambers, vertical shafts, flooded tunnels, and volcanic fractures extending deep beneath the ocean floor. The caverns are completely isolated from sunlight, yet they are far from dark. Vast colonies of bioluminescent organisms cover the walls in blue, violet, and ghostly white light, while towering crystal formations glow from geothermal energy rising through cracks in the rock. Some chambers are so enormous that the submarine's sonar cannot locate the opposite wall, creating the unsettling impression of sailing through an underground ocean. The environment becomes increasingly hostile as the crew travels deeper. Crushing pressure, near-freezing water, sudden geothermal vents, violent underwater currents, collapsing passages, and intense electromagnetic disturbances interfere with navigation and communications. Compass readings become unreliable, sonar returns echoes from passages that seemingly do not exist, and electrical equipment occasionally activates or shuts down without explanation. Stranger still, the crew discovers currents flowing against gravity, apparently disappearing through enormous shafts descending farther into the crust. Life inside Thalassa has evolved in complete isolation. Transparent predators stalk the darkness, enormous jellyfish-like creatures drift through cathedral-sized chambers, armored crustaceans hide among the rocks, and colonies of tiny luminous organisms pulse together as though communicating. Some creatures are attracted to the submarine's lights; others immediately extinguish their own bioluminescence whenever the vessel approaches. Occasionally the crew sees something enormous moving beyond the searchlights—too distant for identification but large enough to produce a significant sonar return.