Sea serpents have fins along their bodies and tails, adapted for swimming. Their scales vary widely in color, although the most common colors are some shade of blue, grey, white, or sometimes green. They are far uglier than dragons, sometimes slimy rather than scaly, more like an eel than a snake. Like a shark, they sometimes have many rows of teeth, and a few may have other mutations, like multiple eyes or glowing lines on their body.
Sea serpents are said to possess a wide variety of abilities. Most tales agree that they do not breathe fire like true dragons, but they may spew noxious venom, and a few stories even speak of lightning powers. They vary tremendously in size, and the oldest are said to be large enough to swallow entire ships whole. Most are not highly intelligent enough for speech, but can be quite clever, and are extremely difficult to kill.