Lake monsters and Sea monsters: a personal Opinion.

So what is a lake monster really?
There are a lot of theories that they are some prehistoric creature like a plesiosaur a sea going dinosaur to the zeugludon like basilosaurus a prehistoric whale. both grew to 50 to 80ft in length.
some theories suggest that these creatures or descendants were landlock when the lakes were cut from the seas millions of years ago.
and thus gave legends of water horses, water  dragons, etc.
I think it is possible. However there is also possibility that people are actually seeing
supernatural entities that manifest themselves in  our world now and then along  side with living  creatures:  descendants of prehistoric creatures.
Our world i believe as is the universe is multi dimensional.