Kraken

Kraken (plural - Krakens) - legendary sea monster of giant size, said to have areal at the coasts of Norway and Iceland.

The legend may actually have originated from sightings of real giant squid that are estimated to grow to 13 metres (46 feet) in length, including the tentacles. These creatures normally live at very big depths, but have been sighted at the surface and reportedly have "attacked" ships.