The cooling of the surface and the constant atmospheric storms eventually forced a segment of the Gorgon population into the oceans. These were the Deep-Walkers, monstrosities that traded their legs for powerful flippers and their armor for streamlined, pressure-resistant skin. They did not simply swim; they colonized the abyss. In the crushing depths of the midnight zone, they encountered the remnants of the ancient aquatic world—giant squids and prehistoric sharks—and promptly annihilated them, assuming their place at the top of the food chain.
The Deep-Walkers evolved to tap into the hydrothermal vents of the ocean floor, much like their ancestors had done on land. However, the high pressure of the deep sea condensed their bioluminescent energy into something far more volatile. They developed the "Sonic Lance"—a concentrated burst of sound that could boil the water around a target, cooking it instantly from the inside out. This weapon was so powerful that a single Deep-Walker could take down a whale-sized creature from miles away, the shockwave shattering bone and rupturing organs with surgical precision.
On land, the surface-dwellers felt the tremors of the underwater wars. The Deep-Walkers were growing larger than any land-based creature could ever hope to be, supported by the buoyancy of the water. Some grew to the size of small islands, their backs covered in coral-like growths that housed smaller, parasitic sub-species. These "Living Reefs" moved across the ocean floor like slow, inexorable mountains. They developed complex, whale-like songs that could travel across entire oceans, allowing the Deep-Walkers to maintain a global network of communication that the land-dwellers could never match.
This split in the Gorgon lineage created a biological rivalry that would last for eons. The Deep-Walkers began to influence the tides and the currents, using their massive bulk to displace water and flood the coastal regions where the land-based Walkers resided. They were the masters of the "Inner Space," and they looked upon the surface world with a cold, predatory disdain. Occasionally, a Deep-Walker would beach itself—not by accident, but as a challenge, a massive wall of blubber and muscle that would rot for years, poisoning the air and the ground around it to spite its terrestrial cousins.
The Deep-Walkers also discovered the "Deep-Veins"—underwater tunnels that led into the hollow spaces of the Earth's crust. They began to migrate into these subterranean seas, finding pockets of ancient, trapped heat that had never been touched by the Great Impact. Here, they evolved into even stranger forms, becoming blind, translucent gods of the dark. The struggle for the planet was no longer confined to the ash and the sky; the very oceans were now a weapon in the hands of the Gorgon kin, and the deep places of the world were being claimed by a force that had forgotten the sun entirely.