August 2014, and Ål, the world's oldest eel, dies in a well in Sweden at the age of 155. He was, reportedly, grotesquely grown, with oversized eyes and other aberrations stemming from his advanced age and over 150 years of living in pitch darkness.

Down a well.

Under a house.

The 1700-1800s, and vessels are lost in the roiling chthonic expanse of the Sargasso Sea, then found again years later, ship shape and afloat but crewed by skeletons or nought but the wind.

Slimy serpents crawl on the slimy sea, maddening lost mariners with inhuman countenance and form.

The Lambton Worm

The Crusades (1095-1272ish), and a rebellious young nobleman skips church to go fishing instead.

He catches a hideous black worm, and when he is reliably informed that he has caught The Devil, he throws it down a well and into his estates' water supply.

The young nobleman, John Lambton, subsequently repents his foolish ways and joins the Crusades as penance.

Lambton distinguishes himself in the fight against the Saracens and is knighted.

Whilst he is away, the worm in the well grows, both in size and malevolence.

It becomes large enough to wrap itself around a nearby hill, breathes out poison fog, eats livestock, children and horses and heals its wounds faster than the local men can inflict them.

When Lambton returns from the Crusades, he finds that the worm has relocated to the River Wear, and has wrapped itself around a rock.

Seized by guilt, civic duty and a commitment to preserving the local fishing industry, Lambton swears he will vanquish the beast he unleashed upon his land (and incidentally the peasant villagers).

John Lambton takes counsel from a local witch, as any God fearing crusading knight would, and is given the following information:

Fix arrowheads to your armour

Fight the worm in the river, not on land

Killing the worm will level a curse. You must slay the first living thing you see afterwards, or your line will be cursed for nine generations

John followed the first two points to the letter.

The worm tried to coil itself around him, but suffered terrible wounds from the arrowheads fixed into Lambton's armour.

As he hacked the flesh from the worm, the River Wear washed the pieces away before they could heal, and soon the great worm was slain.

As for the last piece of advice, John has arranged for a dog to be released once the worm was dead, so that he could kill that and prevent the death curse of the worm from settling on his family. Unfortunately, his father was so overjoyed by his sons victory that he ran to him before the dog. John was unable to kill his own father, and so the curse fell and claimed his life and the lives of his descendants throughout the years.

The Lambton Worm is a fine example of a Dragon or Wyrm or Sea Serpent that you can include in your game, and even features a built in tactic for slaying the beast at the climax.

And a death curse. Wow.

Who doesn't love a death curse?

Identifying the Monster...

What was the Worm? It was described as having nine gill holes on the neck, which suggests that it was a Lamprey.

Some breeds of lamprey are pure nightmare fuel, so that's conceivable.

However, I believe that the worm was a monstrous European Eel.

European Eels were traditionally placed down wells to keep them clear of insects and pollutants. This practice extends their lives significantly, as European Eels do not reach maturity until they migrate to their breeding grounds, which triggers their growth into adults and their ultimate death. If they do not migrate, they do not mature into adults. If they do not mature, they don't breed. If they don't breed, they just keep on living.

Because John Lambton cast the demon worm down the well, he created an environment in which the worm could grow unchecked.

Eels can travel some distance across ground, a behaviour which assists their migration, thus a monstrous eel could move from the well, to the hill, then to the River Wear, consuming sheep and children as it goes.

...And Its Home

And where do Eels migrate to? Where do they breed? The Sargasso Sea, part of the North Atlantic Gyre, an area of dead calm and stagnant water comprising a significant portion of the Bermuda Triangle.

Coincidentally. Where mariners have reported lost vessels, ghost ships and monstrous serpents slipping through the foul seaweed for centuries.

The Sargasso is also known as 'The Horse Latitudes', reportedly because ships caught in the gyre eventually had to pitch their horses (and other livestock) overboard to preserve fresh water.

I imagine that a monstrous sea beast would welcome the addition of horse meat to its diet, and conceivably follow the donating vessel back to port, hoping to taste more rare flesh.

Some believe that the Loch Ness Monster is a massive eel, although 'experts' challenge this assertion, pointing out that eels cannot raise their heads sufficiently out of the water to achieve Nessie's trademark profile. But what do they know?

American Eels also migrate to the Sargasso to breed, allowing the continental North America the opportunity for water monsters as well (Ogopogo, anyone?).

Wrapping Worm Coils Around Your Game

How can you include such a beast in your game?

If your party are at sea, trap them in a calm. Give them glimpses of great beasts moving in the depths below. Throw in a couple of crew disappearances. Eventually make them throw something edible overboard to preserve rations (like a goat) before they escape.

One of the serpents, with an acquired taste for land meat, follows them home, hungry for flesh.

If you're running a landlocked game, then play it straight from the Lambton Worm. Foreshadow the incoming plot by having an NPC speak of a horrible fish he saw, and how some young fool threw it down the well.

Give it a few sessions, then start introducing cattle loss into the narrative. Then move onto missing persons. Finally, there's a giant serpent wrapped around a local hill, poisonous smoke billowing from its maw.

Should the party choose to assault the worm at this stage, be prepared to heavily wound them. They need to understand that the worm cannot be defeated by conventional means, and that special tactics are required.

This should trigger a quest to find a means to defeat the worm, which should, in turn, lead the characters to a wise woman / witch / crone / dubious sexist trope who will instruct them in how to fell the beast.

I recommend that you play up the blood curse. Lifting a blood curse is the stuff that epic campaigns are made of.