Beneath the sea-ice of the Antarctic lies the remains of Shackleton's ship. The strongest wooden vessel ever built, its greenheart timbers are now home to crinoids and sea cucumbers. In its crushed hull: an explorer's bicycle, a biologist's specimen jars and rocks removed from the belly of a penguin.

This week Endurance22 sets sail in search of its famous namesake. It won't be easy, says marine archaeologist Mensun Bound. The constantly moving pack ice makes it a "vicious, lethal environment." Shackleton called it the "worst sea in the world".

In November 1915, this "cruel, evil sea-ice" squeezed and then swallowed the explorer's steam yacht. With no hope of rescue, the crew faced almost certain death. But Shackleton braved 800 miles in a lifeboat over rough seas to reach a whaling station and safety.

It is the stuff of legend. All 28 men survived, their epic tale immortalised in remarkable footage by Frank Hurley.

And thanks to Captain Frank Worsley's logbook, sextant and chronometer, scientists have narrowed their search to a 7-mile by 14-mile zone in the Weddell Sea.

But why risk ice floes and frostbite to find a 100-year old relic? It is proof of the powerful legacy of the Anglo-Irish explorer, who some say was the greatest who ever lived.

He was one of the main adventurers in the Heroic Age of Antarctic Exploration. He led three expeditions, coming within 97 miles of the South Pole. However, he is best remembered for his courage on the Endurance expedition.

Fellow explorer Frank Wild said Shackleton was "the Boss, a great explorer, a great leader". Business schools study his leadership skills. His life is celebrated in countless books and films. A biscuit he once gave Wild sold for £1,250.

But not everyone loves Shackleton. In 1915, a journalist asked why he was "messing about on icebergs" when thousands were dying in World War One. His critics say he was more interested in fame and fortune than scientific discovery.

A "deluded fortune hunter", says writer Jonathan Raban. He risked his men's lives with poor planning and overly optimistic expectations. Compared to Roald AmundsenA Norwegian explorer. He disappeared in 1928 while flying on a rescue mission in the Arctic.'s conquest of the South Pole, or Scott's self-sacrifice, his expedition was a "polar stunt" that went horribly wrong.

His brilliant self-promotion left many tall tales. Allegedly, he put an ad in The Times: "Men wanted for hazardous journey". He promised "bitter cold", "constant danger" and "doubtful" survival. Thousands responded. It's a good story, but there's no evidence it ever existed.

However, the shipwreck does exist, some 3,000 metres below the sea ice. Two underwater drones will make a detailed 3D scan, but nothing can be removed. The site is protected as a historical monument by international law.

The discovery may inspire future explorers and scientists. Like sea-ice researcher Stefanie Arndt, onboard Endurance22. "This is huge," she says. "The first book I read about Antarctica was about Shackleton. It was my kickoff into polar science."

Yes: Exploration is about doing the impossible. And nothing compares to Shackleton's 17-day voyage in a tiny boat across the Antarctic Ocean followed by a 34-hour climb up a glacier to safety.

No: Shackleton fans have short memories. What about Colombus crossing the Atlantic? Or Ferdinand Magellan's circumnavigating the globe? There is stiff competition for the title of greatest explorer ever.

Or... Perhaps we don't need heroes. Shackleton's story is complicated - he had strengths and weaknesses. But every explorer needs a team, so we should spend more time celebrating cooperation and teamwork.