Sea serpent is a creature from Norse mythology. Other names for this creature are sea dragon, Sea Orm or Jörmungandr. It is a type of unclassified marine animal. Throughout the history, there were countless reports of people seeing some sea snake. Animals that people are usually seeing and believe to be sea serpent are whales, lungfish, oarfish or sharks. Sea serpents are usually relict of Mesozoic marine reptiles. There are some stories which said that sailors mistake back of a monster for a chain of islands.
Jörmungandr or Midgarðsormr was a mythical creature from Norse mythology ant it was so long that could encircle the whole world, Midgard. There is a legend that Saint Olaf killed a sea serpent in Valldal, Norway in 1028 AD and threw its body onto the mountain Syltefjellet which left a mark on the mountain. In the book, Carta marina written by Olaus Magnus can be found a lot of sea monsters including a sea serpent. Magnus also describes a Norwegian sea-serpent in his book History of the Northern Peoples.
Many cultures and people from Mediterranean and Near East also believe in sea serpents and have many myths like Babylonian Labbu and stories like Aristotle's Historia Animalium about them. Laocoön, from the Latin epic poem Aeneid, was killed by a pair of sea serpents.
There are some passages from the Bible which mention sea serpents: in Book of Genesis 1:12 there is a reference to “great creatures of the sea” and The Book of Amos mentioning a serpent which bites people who are hiding from the God in the sea.
There is a story by Greek geographer Strabo that his colleague, Poseidonius saw a dead sea creature on the coast of the northern Levant. It was 100 feet long, with the jaws so huge that a horse could fit in. This happened between years 130 and 51 BC.
Another story about sea serpent was told by Hans Edge, the national saint of Greenland. As he and his crew sailed past the Greenland coast, they saw a huge creature. That creature was something they never saw before. When the creature lifted is heat it was higher than the mainmast of the ship, and it was longer than the whole ship.
From 1638 onwards there has been a lot of reports about sea serpent sightseeing. However, none of that reports have solid proof. Sailors of a nineteenth-century warship of the Royal Navy HMS Daedalus said that they saw the creature that is 60 feet long with a snakelike head. Sir Richard Owen, English biologist of that time explained that it was probably an elephant seal what they saw.
Yuio Maru, the Japanese fisherman, caught a carcass of a creature that was unknown to him near the coast of New Zeland on April 25, 1977, and scientist took a photos and tissue specimens. First, they thought that it was a prehistoric plesiosaur, but later it was confirmed that it was a carcass of a basking shark.