A planet in a distant star system, Hydross is a world covered entirely by water, due to being so close to the sun it orbits. Hydross is populated by vast coral reefs and fire-breathing Sea Serpents. Due to the high global temperature, hurricanes and other tropical storms occur frequently on Hydross.
After the Core was finally defeated by the Arm rebellion, an activation signal was sent to a Core Commander lying dormant beneath the vast oceans of Hydross. His mission was to carry out the Core Contingency Plan to find an alien artifact that could be used to create a Galactic Implosion Device that would collapse the entire galaxy, which would destroy the Arm and revive Core Empire. The Arm had found out about this plan and clashed with the Core forces on Hydross in extensive naval battles.