In spite of the fact that there isn't a shred of scientific evidence in support of such a belief it will not down. It has existed for centuries and I suppose will continue to exist for more centuries to come. All the sea serpents that have been reported, if they ever were captured have proved to be some already known fish or animal.
Faulty observation is responsible in most cases.
An animal at sea, as a rule, gives only a brief glimpse of itself. Perhaps it is a whale or a shark or a seal which is unknown to the observer. He sees it for a second or two, and only part of the body at one time. A sea serpent, to fit the popular conception, should have a long neck and a head like a camel. Why a camel, God only knows, but a camel-like head it must have.