The world has yet to see concrete evidence proving the existence of a monster at the bottom of the lake. There are photographs, many of which have been dismissed as pieces of debris in the water, or other "real" animals, like dogs. One of the most famous Nessie photographs was taken 1934 by London surgeon R. K. Wilson. Disbelieving naturalists state that the ripples around the neck of the creature are too large, and conclude that it is a diving otter or marine bird, such as a moorhen.

In 1964 the Loch Ness Investigation Bureau established a permanent presence around the Loch with camera stations in many locations. They had vans, which served as mobile camera stations, and underwater listening devises.

Several scientific studies have been conducted using advanced technology such as hot-air-balloons, infrared nighttime cameras, sonar scanners, and submarines. Since much of the undiscovered Earth lies underwater, it is appropriate to assume that there are many creatures unknown to humans.

In 1987, Operation Deepscan led by Adrian Shine, displayed a line of 19 motor cruisers stretched out across the width of the loch. Each vessel had on board sonar. A second line of vessels also armed with sonar followed these boats. These sonar searches uncovered unknown data upon the lochs underwater storms but except a few traces, no creature was spotted swimming under the lake.

However, the size (21 square miles) and great depth of the loch (more than 800 feet), together with potential passages to other lakes, gives the monster many places to hide. Moreover because of the murkiness of the water, it is almost impossible to see anything below 10 m.

The 1972 visit of the Academy of Applied Science produced an underwater photograph, which, with the aid of computer enhancement, revealed a flipper shape. Again these photographs were criticised, some claiming that they showed nothing but debris at the bottom of the loch, a tree trunk or even the head of a dummy monster sunk some year previously during the filming of a Sherlock Holmes movie.