Palaeophis is an extinct genus of snake. The sea

Sea

A sea generally refers to a large body of salt water, but the term is used in other contexts as well. Most commonly, it means a large expanse of saline water connected with an ocean, and is commonly used as a synonym for ocean...

-dwelling creature was initially thought to have been the largest snake ever, reaching the almost mythical length of 30–40 m (100-133 ft), but recent estimates put its length at about 9 m (30 ft), about as long as the modern green anaconda and reticulated python. One species, P. casei, was rather tiny, however.