Sea Dragons are a class of dragons containing (in the books) Seadragonus Giganticus Maximus, Doomfang and Sharkworm, amongst others. In the film franchise it includes all the tidal class dragons. Many of the Sea Dragons in both the books and the film franchise are very large. Some can fly, others cannot. A few breathe fire, but many (like the Scauldron, Bewilderbeast, Thunderdrum, and Doomfang) use an alternative or even water based form of attack.