"I couldn't believe my eyes when I saw this jet black thing, about 45-feet (15 meters) long, moving fairly fast in the water," said Gordon Holmes, the 55-year-old a lab technician from Shipley, Yorkshire, who took the video this past Saturday.
He said it moved at about 6 mph (10 kph) and kept a fairly straight course.
"My initial thought is it could be a very big eel, they have serpent-like features and they may explain all the sightings in Loch Ness over the years."
Nessie watcher and marine biologist Adrian Shine of the Loch Ness 2000 center in Drumnadrochit, on the shores of the lake, viewed the video and hopes to properly analyze it in the coming months.
"I see myself as a skeptical interpreter of what happens in the loch, but I do keep an open mind about these things and there is no doubt this is some of the best footage I have seen," Shine said.
He said the video is particularly useful because Holmes panned back to get the background shore into the shot. That means it was less likely to be a fake and provided geographical bearings allowing one to calculate how big the creature was and how fast it was traveling.
[T]here have been more than 4,000 purported Nessie sightings since she was first caught on camera by a surgeon on vacation in the 1930s.
Since then, the faithful have speculated whether it is a completely unknown species, a sturgeon -- even though they have not been native to Scotland's waters for many years -- or even a last surviving dinosaur.
Shine doubts that last explanation.
"There are a number of possible explanations to the sightings in the loch. It could be some biological creature, it could just be the waves of the loch or it could be some psychological phenomenon in as much as we see what we want to see," he said.