Beneath the ice of the Antarctic lies Shackleton's ship. Its greenheart timbers are 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 namesake. It won't be easy. Shackleton called it the "worst sea in the world".

In November 1915, this "cruel, evil sea-ice" swallowed the explorer's steam yacht. The crew faced almost certain death. But Shackleton braved 800 miles in a lifeboat to reach a whaling station and safety.

All 28 men survived, their epic tale immortalised in footage by Frank Hurley.

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.

Why risk ice floes to find a 100-year old relic? It is proof of the legacy of the explorer, who some say was the greatest ever.

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. 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".

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 interested in fame and fortune.

A "deluded fortune hunter", says writer Jonathan Raban. 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. There's no evidence it ever existed.

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

The discovery may inspire future explorers. 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.