I am trying to find the title of a Loch Ness novel that I read decades ago. (1980 copyright, I believe) A scientist invented a computer-camera system which could see through the murky waters of Loch Ness, and he launched an expedition to film the monster. The waters of Loch Ness are filled with suspended particles of peat, with the result of low visibility. The camera system worked by only recording the light which reflected from objects at a preprogrammed distance.
Espionage was involved, as foreign spies tried to acquire this camera system for their own use. In the end, the Loch Ness Monster proved to be a human mutant, created by ancient Druidic sorcerers as a weapon against the Romans.
The Druids raised the mutant in a sensory-deprived environment.
People in sensory deprivation tanks have been known to hallucinate, and the novel's author uses the theory that sustained sensory deprivation could lead to the development of psychic powers.
The novel's protagonist had no special training, yet he was able to deal with the espionage agents on equal terms; another character referred to the protagonist as "A natural". This novel also has several flashbacks to various ancient times, the first being from the viewpoint of the Roman soldiers in pursuit of the Druids who created the mutant. Another flashback is with a group of Vikings who bring one of their ships to Loch Ness; the ship is struck from below and sinks in the loch. Another flashback is from the viewpoint of a young lady who was born 'slow'. This girl senses a friendly presence in the loch, experiencing dreams of swimming underwater with something beautiful which she never sees. At the end of this flashback the creature reveals itself to her during waking hours, and she rejects is plea for friendship, horrified by its appearance.
The mutant is motivated by lonesomeness throughout the novel, afraid of the outer world, but hoping to find a human who is not afraid of it. The novel also refers to a legendary supernatural border around Loch Ness, inside of which people could be influenced by witches. The novel implies that this border is the limit of the psychic mutant's power.