The Morag attack on Duncan McDonell and William Simpson's boat, Loch Morar 1969

Loch Morar lies in the Rough Bounds of Lochaber, in the Scottish Highlands. It is 18.8 km long and 310 m deep, the deepest freshwater body in the British Isles. Morar village sits at its western end, between Arisaig and Mallaig. People there called what was said to live in the loch Morag. Reports date to the 1880s, and by 1981 Janet and Colin Bord had counted 34 incidents, 16 with more than one witness.

August 1969. Around 9 pm, but still daylight. Duncan McDonell was at the wheel of a motor boat with a small cabin, heading along the loch at six or seven knots. William Simpson was aboard.

A kettle sat on the gas stove. Then came a splash behind them. "As we were sailing down the loch in my boat we were suddenly disturbed and frightened by a thing that surfaced behind us," Simpson later said. McDonell saw it about 20 yards back. It was moving directly towards them.

A few seconds later it caught up and struck the side of the boat. The blow hurled the kettle off the stove and onto the floor. McDonell grabbed an oar and tried to push the animal away. He was afraid it would capsize them. The oar was old.

It snapped in half. "Then when I seen the oar break I grabbed my rifle and quickly putting a bullet in it fired in the direction of the beast," Simpson said. The creature slowly sank away from the boat. There was no sign it had been hit.

The men described an animal 25 to 30 feet long, brown, with rough skin. Three humps rose about 18 inches above the water. Its head was about a foot wide and snake-like, held 18 inches clear of the surface. Simpson came away certain. "There is no doubt in my mind that there is a large monster, maybe more than one, in Loch Morar."

In 1970, members of the Loch Ness Investigation Bureau formed a Loch Morar Survey. The encounter on McDonell and Simpson's boat is said to have prompted it. Over three years the survey gathered about 38 sighting reports and concluded there was "a genuine mystery justifying investigation." Elizabeth Montgomery Campbell and David Solomon set out the case in The Search for Morag in 1972.

In 1975, Adrian Shine led an expedition that lowered an observation sphere, the Machan, about 30 feet down. It found "no unknown skeletal remains." Later teams turned to underwater television and sonar. By the mid-1990s, one encyclopedia concluded that "no clear evidence of Mhorag has been produced."

The retellings do not agree. In one, the boat struck the animal and provoked it. In another, the animal hit the boat by accident. In a third, it rammed the boat side-on in a deliberate manner. The rifle becomes a shotgun in one version. No 1969 newspaper report has surfaced, and the men's own words survive only through much later accounts.

For Morag in general, the explanations run from large trapped eels, swimming deer and seals to a stray Atlantic sturgeon, with a surviving plesiosaur at the far end. None has been tied to this encounter. Nobody has called it a hoax either. Like the Mackays' sighting on Loch Ness in 1933, it remains a single vivid moment on dark water that nobody has been able to explain.