Many ships can and have been overturned by the massive so called monsters. It is said that in the 1860's a animal similar to a whale shark caused the loss of some sailors. This could be due to the shark causing the boat to either flip over, or the shipmates all jumped off in fear. New research in understanding fossilized shark teeth have lead to advancements in understanding these monsters of the sea. The fossilized teeth as well as stories from history help provide information as to what sailors really did see. In 1875 it is said that a "a sperm whale with a snake-like creature wrapped around it's mid-section" was seen. The crew reported this sea serpent eventually dragged the whale down to it's death. With a better understanding of the ocean it is thought that what these sailors saw was a squid battling a whale, seeming highly possible.
There are many creatures of the sea that could be considered monsters. We have yet to discover many of the monsters of the sea. There is so much yet to discover about the sea. As the we learn more about these monsters the sharks, octopi, and squids the ocean becomes more and more interesting!