and there's no simple explanation in loch ness for what that could have been. >> dinsdale's film also adrian shine to identify once and for all what lies beneath the surface of lake ness. >> the loch ness monster is an amalgam of many things put -- perhaps weld would together by the human consciousness, by human perception, by human aspiration. we'd all love there to be something there. >> adrian's loch ness project has organized dozens of expeditions from operation deep scan, a 24-boat sonar exploration in 1987, to submarine searches, and even an exorcism. >> be gone now, hideous demon. >> but nessie has remained a no-show. >> i think the legend is popular because we see dragons. and also, in a way, we like our mysteries to be something we can half comprehend as well. loch ness is one of the places where anybody can come. there's a road around it. it's not the antarctic. it's not outer space. it's not the bottom of the ocean. looking for monsters in a lake with a road around it is a mystery we can all join in with. >> when i finally see something in the loch, i really don't know what