I have written about this before but that post focused more on Lerna as a whole.
Although artists and poets disagree about the number of heads the Hydra is described consistently as multiple heads that were snake like and a thick trunk and the ability to grow back any head that was removed and as being amphibious.
The word Hydra means Water serpent.
The creature was said to have out of the wetlands adjacent to Lake Lerna which has now silted up and become farmland and made a lair near the source of a sacred river or the springs from which streams flowed that converged into a river. These have also disappeared apart from one last small pond.
In ancient times Lerna south of the lake was an area of springs and several shrines and cults. Settlement here dates back to the Helladic and this is the location of the famous House of Tiles.
This site is south of the modern village of Myloi the Mills.
Now notice that like the Hydra the river had MULTIPLE SOURCES.
While the Hydra could have been one creature Heracles was also famous of opening springs diverting rivers building walls ... he was some sort of engineer.
How does Heracles defeat the Hydra? He cuts off and then burns the stumps of the heads and one head is buried under a rock?
The stumps are burnt with wooden brands!
Now charcoal is used as a water filter and several writers have suggested the Hydra was a nick name for malaria.
If heracles had been fighting a malaria outbreak he would tried to divert the waters away from the wetlands maybe by opening an extra channel to the sea.
Instead he fights the Hydra near the source of springs.
I'm thinking somehow one or more of the springs became contaminated with a virus or bacteria and cutting off the heads is a metaphor for having to cut off the springs and block one source ... the head under a rock ?
Perhaps he had to temporarily block each source to work out which one was contaminated and then permanently block that one?
Or there was an infestation of snakes and he burnt down grasslands and shrubs around the springs?
Or even both with the snakes mistakenly being thought the source of a plague of some sort?
however whether the Hydra was a supernatural monster a plague or too many snakes Heracles acted to help commoners by ending its attacks.
It also inspired this famous Italian Renaissance painting.
I hope you enjoyed the vase painting images I found. You can Google Earth Lerna and see the last remaining spring. Enjoy!
Next Time Over hill and dale. Heracles hunts a sacred deer or reindeer?