Loch Ness is a deep lake in Scotland. The lake is so dark, it is very hard to see anything underwater. But more than four thousand people have reported seeing a monster in its waters.
Stories about the Loch Ness Monster go back hundreds of years. The ancient Scottish people who lived near the lake told tales about the creature.
People describe the monster as being as big as a school bus, and having a wide body, fins, a long neck, and a tail. The monster has even been given the name Nessie.
Scientists have used machines to search the dark waters of Loch Ness. Not even the most expensive cameras, submarines, or other devices have found Nessie. The rocky bottom of the deep lake makes it easy for a clever sea beast to hide.
Scientists have taken photos in the lake. The pictures show something large, but are cloudy and unclear.
Some think Nessie could be a strange type of giant eel or a type of whale or seal that no one has ever seen before. Another idea is that Nessie is a relative of a prehistoric fish called the plesiosaur. Maybe Loch Ness has the right conditions for Nessie and her relatives to live and hide.
Would you go swimming in Loch Ness?