The Cerulean Snake is a type of venomous water snake found in rivers and lakes. They are very territorial and can spit a very high power blast of water from their mouths. The snake is born small and naturally only grow to the size of a garter snake.

Some of these snakes have a blue gem placed in he middle of their head (as pictured above), these are known as the Cerulean Deathwhip. It's said that the gem (called the Cerulean gemstone) keeps them alive forever, and allows them to continue to grow to massive sizes. They are not born with the snakes, but only passed along to another snake when a Deathwhip dies. This version of the snake is unaffected by saline content in water so could theoretically live happily in the oceans.