The Loch Ness monster

Our world is full of mysteries and secrets. And even the usual places that are full of people have their own secrets. There are so many insects, animals and viruses that were not discovered till now and we don't know anything about their existence.
The lake Loch-Ness has its mystery too. According to stories an ancient monster lives in this lake.
The first information we get from the stories of Romans. The images of a long-necked seal were found that conserved from the times of Ancient Rome. According to other legends this monster was like a frog but not the real frog.
Some people believe in this monster, others don't. But people can't say exactly whether it exists or not. The main argument of sceptics is the fact that the number of biomass in the lake is not enough to feed a monster of huge sizes. In spite of a great size and abundance of water this lake has, its flora and fauna are very pour. During investigations that were held in this lake a lot of kinds of animals were discovered. But sound scanning showed that this lake has biomass of 20 tones that is enough for feeding an animal not bigger than 2 tones. And according to those who believe in existence of this monster, its mass should be 25 tones. Besides, they base their arguments on legends and stories that tell about numerous caves and tunnels that are situated at the bottom of the lake that give the possibility to a monster to go to the sea and come back to the lake.
There are several theories that explain the precedence of this monster.
According to the first theory, people simply confused swimming elephants with this monster. When an elephant swims it keeps its trunk over the water and a small part of its back and head may be seen. And most of descriptions of this monster were similar. It was supposed to have a long neck (trunk).
According to another theory, there is a huge joint fissure at the bottom of a lake known as Great Glen. And huge waves, bubbles and strange sounds may appear thanks to this Great Glen. And these strange things that may happen may be confused with monsters.
Another explanation is connected with business. According to it one of the businessmen that had business near this lake published photos and articles to attract tourists.
But till now the mystery of this lake wasn't discovered and scientists try to find some proofs or denials of existence of this monster.