Lerna Heracles killed it, as the second of his labors. The strong Karstic springs remained; the lake, diminished to a silt lagoon by the 19th century, has vanished. Lerna is notable for several archaeological sites, including an Early Bronze Age structure known as House of the Tiles, dating to the Early Helladic period II (2500–2300 BC). The secret of the Lernaean spring was the gift of Poseidon when he lay with the "blameless" daughter of Danaus, Amymone. The geographer Strabo attests that the Lernaean waters were considered healing: Lake Lerna, the scene of the story of the Hydra, lies in Argeia
HMS Hydra (A144) the first commission of HMS "Hydra". She was decommissioned and sold to the Indonesian Navy in 1986 and renamed KRI "Dewa Kembar" (Pennant Number 932); she was still in service in 2006. There have been eight ships of the name in the Royal Navy, named for the Hydra of Greek Mythology, a serpent with many heads (though nine is generally accepted as standard), the centre one of which was immortal. The monster was overcome and slain by Hercules. The ship's badge of HMS "Hydra" depicts the monster with seven heads. The ship's motto was "Ut Herculis Perseverantia" ("Like Hercules Persevere").