For boss information, see Hydra (Monsters).
The Hydra are a reptilian species that occupy the Hydra Marshes. Their physiology purifies the water of the area, keeping its PH level above acidity. The unique nature of its secretions also allowed them to be used as a panacea on Humans; once El Nido was settled in 920 A.D. by mainlanders, the Hydra were poached. By 1010 A.D., they had been reduced significantly in number. In Another World, the last one was killed some time before 1020 A.D.; the swamp subsequently turned into an acidic mess, and many creatures perished. In Home World, the last Hydra was killed in 1020 A.D. (by Serge or another); it fortunately was pregnant at the time, and the baby was successfully birthed post-mortem. It was taken care of by the Dwarves thereafter, granting the marshes some degree of hope for the future.
12-headed serpent demon in Greek Mythology.