Now for something Historically interesting. This was on a video taken in the 1942, and captured after the War was over. This size has only been seen in fossils of a shark called Megalodon. 

Some people think the Discovery channel doctored this photo, but it doesn't show the cut and paste look that would have been state of the art when this was on their channel, so I doubt this claim. It doesn't make sense, other pictures would have been easier to doctor....

Captured frame from a Nazi Video:
https://www.youtube.com/watch?v=_253vd-8N3s

>Submarine shark caught on tape!! Nazi Secret Exposed. Photo Shows Shark size of a U Boat! Megalodon teeth are killing machines! A Megalodon tooth measures up to a foot long! Two main species of Megalodon are the Carcharocles Megalodon and the Carcharodon Megalodon, both of which were thought to be similar to the Great White Shark but over 100 feet in length! I think this footage is one of the best megalodon shark caught on tape videos out there!

Estimates of the size of this beast is 110 foot long, about five times the size of a great white shark. This was taken off the horn of Africa, where a deep creature like this would have to come shallow to move between the Atlantic and the Pacific. 

Two things lend credence to this picture. First they did not have the ability to modify video films in the 1940's. Second the fish fits with the surface, including Spray in front of the dorsal fin from a wave and easy forward motion. If I were 110 foot long, and had a mouth full of foot long teeth; I wouldn't rush either, LOL!

I would also point out that this was a film to show the 'might' of the Uboat fleet, and the shark is a distraction to their message; so there is NO military reason to 'add' a shark! 

I don't know, but they were sure the Coelacanth was extinct even recently. Now we know that it is, in fact, not extinct!

https://en.wikipedia.org/wiki/Coelacanth

This Megalodon beast would be a little harder to 'catch' in a net, or on a line...so I am keeping an open mind. But we have NO idea what lies in the depths of the ocean; we have explored less there, than we have in outer space. When you are talking about thousands of square miles of open ocean, a fish, even one this big; can easily go unnoticed!