A giant eel is one of the most feared sea monsters, well known for being one of the weakest monsters to possess the infamous two-move instadeath drowning attack. There are always several giant eels and sharks in the castle moat. Like all sea creatures, they are never randomly generated, but appear as part of levels and rooms with water. Giant eels generated this way have an 80% probability of starting out asleep if you haven't yet gotten the Amulet of Yendor.
The behaviour of eels in fresh water extends the air of
mystery surrounding them. They move freely into muddy, silty
bottoms of lakes, lying buried in the daylight hours in summer.
[...] Eels are voracious carnivores, feeding mainly at
night and consuming a wide variety of fishes and invertebrate
creatures. Contrary to earlier thinking, eels seek living
rather than dead creatures and are not habitual eaters of