For many years,  witnesses have claimed to have seen a unknown creature in Loch Ness in Scotland.  The lake was cut off from the sea just a few thousand years ago.  The creature is usually described as being  maybe twenty feet long.  People have speculated that the creature may be a non - extinct species of plesiosaur,  a long - necked creature described as being like " a snake threaded through a turtle". Other similar creatures have been reported from other fresh water lakes,  such as Lake Champlain.

There are several problems with this scenario.  Biological studies of Loch Ness have shown that it does not contain enough fish to support even one large creature,  let alone a breeding population.  Biologists agree that it would be very unlikely there could be just one or two such creatures.  The outlets to the lake consists of a very shallow "river" and a canal with locks.  Apparently neither waterway would readily permit very large creatures to enter or exit the loch without being observed.

If they were air breathers,  under perfectly calm conditions,  there should be obvious disturbances when the creatures periodically surface for air. A stable breeding population would have to surface many times a day, probably several times an hour.  Surfacing whales are certainly obvious at quite a distance.  No one has ever reported seeing that in Loch Ness.  A sweep of the entire lake with wide - scan sonars,  from one end to the other,  failed to show up a large creature of any kind.

Some of the photos of "Nessie" have been shown to be a hoax.  The photo of the flipper appears to be impressive.  However,  it was said to have been derived by computer enhancement.  Some investigators claim it may have been over - enhanced,  even to the point it may have been virtually created from a very approximate shape.  The photo of an alleged head was not symmetrical,  unlike almost all biological creatures.

In Lake Champlain,  a lady reported seeing a large creature, she estimated to be   over twenty feet long.  Apparently being a woman of action,  she took a shot at it.  The next day, a large sturgeon with a bullet hole in it washed up on shore.  Sturgeon have been reported at well over ten feet in length.  Not much is known about the mating habits of sturgeons.  Like many other creatures,  the males may closely pursue the females.  Such a pursuit  might readily be perceived as several humps of a single creature.

Creatures in the open ocean may be a different story.  People have reported what are called sea - serpents for many years.  One investigator claimed he could plot the ranges of several different species throughout world.  If true,  that would be hard to do for an imaginary creature,  unless the witnesses worked together and somehow managed to keep their stories straight.