IT'S no wonder people once thought the Corryvreckan whirpool was controlled by a sea witch. The gulf can seem a fickle stretch of water. There are times, on a slack tide, when strong swimmers can traverse the calm stretch and divers visit, briefly, the undersea features beneath, and others when it rages, reminding us of why it is one of Britain’s most dangerous diving waters. A documentary team once threw a mannequin, wearing a lifejacket and with depth gauge attached. It was spat up miles away, its lifejacket torn, pockets full of gravel, having been dragged along the bottom, with a depth gauge reading of 262m.

But, of course, the whirlpool has its rhyme and reason. It’s a tidal phenomenon, there and then not, suddenly bubbling up in the waters between Jura and Scarba, turning into a fierce maelstrom on a spring tide. In stormy weather the roar of the whirpool can be heard ten to twenty miles away.

The other marvel of this phenomenon, the thing that makes it such a draw for wildlife-spotting cruises, it that it is rich with life, the rocks beneath a haven for corals, sponges and shellfish, which are themselves food for larger animals and birds: sea eagles, golden eagles, puffins, whales, seals, porpoises.

READ MORE: Mystery of Corryvreckan uncovered by scientists

Such has been its dangers to sailors that it shouldn’t be surprising that there are plenty of dramatic stories attached. Famously, George Orwell only just survived drifting too close when he went out in a boat with his young nieces and nephews when he was staying on Jura, writing 1984. The boat lost its motor, but they fortunately managed to row to a nearby rocky island, where they were rescued by a passing lobsterman.

Among its legends is that of Norwegian prince Breakan, who fell in love with an island princess whose father demanded that he prove himself by anchoring his boat for three days and three nights in the whirlpool. In spite of his having made his anchor rope from maidens’ hair, the boat was sucked under and Breakan drowned. Another says that a sea witch conjured it to protect Scotland from an Irish pirate.

Gradually we are learning the truth. Until recently it was thought that his, the third-largest whirlpool on the planet, was formed when the tidal race between the islands hit a pinnacle in the ocean, but when oceanographers from the Scottish Association of Marine Science mapped the seabed using echo-sound, they found no such feature. Instead, what they discovered to be causing the maelstrom was a steep-sided buttress of rock protruding from the Scarba shore. The mysteries of this sea hag are still only now being revealed.