From A Wiki of Ice and Fire
Sea dragons are possibly mythical creatures of the sea. Some maesters question their existence, as they have not been seen in millenia. Believers think they still exist deep in the Sunset Sea.
It is unknown if sea dragons are related to dragons, although Sea Dragon Tower is a dragon-shaped tower at Dragonstone in the narrow sea. Sea Dragon Point is a peninsula of the north in northwestern Westeros.
According to ironborn legend, Nagga was the first and mightiest sea dragon, a creature which fed on krakens and leviathans. She was slain by the Grey King, however, and her bones formed part of the Grey King's Hall.
- ↑ The World of Ice & Fire, The Iron Islands: Driftwood Crowns.
- ↑ A Storm of Swords, Chapter 54, Davos V.
- ↑ The Lands of Ice and Fire, Westeros.
- ↑ A Feast for Crows, Chapter 19, The Drowned Man.