Well, nobody knows whether the loch ness monster exists or not, except for the photo evidence which mostly has been proven fake. But yes, sea monsters did and do exist, depending on your definition of sea monsters. The loch ness monster is supposedly a plesiosaur, which is a aquatic dinosaur. Bones have been found of these around the UK so it is possible, however they were thought to have died out millions of years ago.
You might find something called a megalodon interesting, look it up and see if this is what you mean by sea monster!
· 9 years ago