As someone whose favorite subject of study is Cryptozoology, I often come across reports of strange creatures that aren't strictly "monsters." Rather, they are animals that are well known, but which have grown to incredible sizes. In times gone, however, tales of those same animals were sometimes exaggerated. Sometimes, however, the creatures really were massive in size. So, with that said, let's now take a look at some of those cases. Adam Benedict provides some fascinating information: “First reported in 1494 by explorer Christopher Columbus near the Dominican Republic, the Father of All Turtles was described as being the size of a whale, while also possessing a long tail with a fin on each side to help with movement through the water. The giant turtle was said to have kept its head out of the water the entire time it swam within close proximity of Columbus’s ship, the Santa Maria. Eventually, the Turtle felt it had spent enough time on the surface and dove back below the surface of the Atlantic where it was seen no more by the explorer and his men.”
Scientific American has stated that in the latter part of the 19th century - specifically 1883 - an enormous turtle was encountered: "Captain Augustus G. Hall and the crew of the schooner Annie L. Hall vouch for the following: On March 30, while on the Grand Bank, in latitude 40 10′, longitude 33, they discovered an immense live trunk turtle, which was at first thought to be a vessel bottom up. The schooner passed within twenty-five feet of the monster, and those on board had ample opportunity to estimate its dimensions by a comparison with the length of the schooner. The turtle was at least 40 feet long, 30 feet wide, and 30 feet from the apex of the back to the bottom of the under shell. The flippers were 20 feet long. It was not deemed advisable to attempt its capture."
A massive creature that features heavily in Scandinavian folklore and mythology, the Kraken is a terrifying beast, perhaps most reminiscent of H.P. Lovecraft’s famous, fictional monster with the name of Cthulhu. A beast of the mysterious deep, the Kraken is a definitive sea monster; albeit, not a sea serpent of the long-necked and hump-backed variety. In many respects, the Kraken sounds like a strange combination of a giant octopus and an utterly gargantuan squid. Certainly, both animals have the ability to grow to significantly large proportions – with the Colossal Squid, reaching overall lengths, including tentacles, of up to forty-six feet. The Kraken, however, is said to grow much, much bigger – and to the point where, in centuries long gone, it supposedly dragged ships under the waves, drowning their crews in the process. A monster? Not in my opinion. The likelihood is that the legends of the Kraken were based on sightings of huge squid.
As someone who had a deep interest in the field of giant squid, Henry Lee collected a huge body of data on the subject – which, combined, led him to believe that there were some true monsters swimming and living deep in the waters of our world; monsters much bigger than had previously ever been recorded. Lee said: "In the American Journal of Science and Arts, of March 1875, Professor Verrill gives particulars and authenticated testimony of several other examples of great calamaries, varying in total length from 30 feet to 52 feet, which have been taken in the neighborhood of Newfoundland since the year 1870. One of these was found floating, apparently dead, near the Grand Banks in October 1871, by Captain Campbell, of the schooner B. D. Hoskins, of Gloucester, Mass. It was taken on board, and part of it used for bait. The body is stated to have been 15 feet long, and the pedal or shorter arms between 9 feet and 10 feet. The beak was forwarded to the Smithsonian Institution."
As the above demonstrates, sometimes a monster isn't a monster, at all. It's just a perfectly normal animal, albeit huge in size.