Sea Serpents can be found in all major oceans and seas. The sizes and presumed breeds of sea serpent varies across the globe, but their general body structure argues for a common evolutionary ancestor with dragons. The Chineese refer to the creatures as kiao, of sea-dragons.
Whilst carrying Temeraire and William Laurence to China in 1806 HMS Allegiance was attacked in the Indian Ocean, by the largest sea serpent recorded by Europeans. The creature was at least 250 feet in length, over twice the size of a Regal Copper, though the bidy was less than 20 feet in diameter. During the attack Temeraire instinctively felt that the serpent was a sentient creature and was disturbed by his inability to communicate with it and the eventual necessity to kill it.