However, there have been enough attacks to confirm their existence. A lone sea serpent is capable of taking down a single ship, though they will hold back if ships travel in convoys.
Sea Serpents have several attacks at their disposal. They produce an acid enough strong enough to dissolve metal, while their immense jaws can cause massive crushing damage. Finally, some of the largest Sea Serpents are capable of wrapping around a ship, and squeezing it into broken lumber.
(Source: Magic Stones)