The REAL reason why Ernest Shackleton's ship sank: Endurance had key structural weaknesses - and the polar explorer knew about them before he set sail, study reveals
It's one of the world's most famous shipwrecks, marooned nearly 10,000 feet deep beneath the surface of the Weddell Sea in Antarctica. Endurance, owned by legendary Anglo-Irish explorer Ernest Shackleton, sank in November 1915 after it became crushed by dense sea ice. Until now, experts have claimed a weakness in the rudder was the supposedly fatal flaw that caused the 144ft-long sailing vessel to founder. But a new study finally reveals the real reason – and it suggests Endurance wasn't quite the magnificent ship it was made out to be. Jukka Tuhkuri, a professor of solid mechanics at Aalto University in Finland, claims Endurance had numerous structural weaknesses that made it notably less robust than other early polar vessels. Endurance lacked a strong structural skeleton, and was never properly equipped to withstand the immense inward pressure of dense ice. Remarkably, Ernest Shackleton was well aware of the ship's deficiencies before he set sail, according to the expert. 'We do not really know why Shackleton went ahead with the mission,' Professor Tuhkuri told the Daily Mail. Famed polar explorer Sir Ernest Shackleton was aware of worrying structural shortcomings in the ill-fated ship, which was found in 2022. Pictured, a 3D printed physical model of Sir Ernest Shackleton's ship on display at Goodwood, West Sussex, July 2025 Endurance wasn't found on the ocean floor for more than a century after its sinking. Pictured, the stern of the wreck of Endurance, Sir Ernest Shackleton's ship, which was crushed by the ice and sank in the Weddell Sea in 1915Professor Tuhkuri was one of 15 scientists who were invited to join the Endurance22 mission, which found and surveyed the lost ship in 2022. Until now, a structural analysis of Endurance as a ship has never been conducted – which he says is surprising, considering it 'had a central role in the fate of the expedition'.His study, incorporating both technical analysis and research into diaries and correspondence, suggests Endurance was simply not fit for purpose. Endurance had several structural deficiencies compared with other early Antarctic ships, including weaker deck beams and frames made of oak and pine. Meanwhile, the 'vulnerable' machine compartment – the part of the ship containing the main machinery, in this case the steam engine – was longer leading to serious weakening in a significant part of the hull. 'The weakest part of its hull was the engine room area, which was not only larger than in other early Antarctic ships, but lacked beams to give strength against compression by ice,' said the expert. What's more, unlike other ships of the time, there were no diagonal beams to strengthen the hull, which could have prevented ice crush. 'Diagonal supports are very effective in stiffening and strengthening a ship hull,' the academic explains. The legendary Anglo-Irish explorer died in his cabin on board the Quest while it was anchored off South Georgia. He was 47 years old. Pictured, Shackleton on board the 'Quest' Pictured, Anglo-Irish sailor and explorer Frank Wild assesses the wreckage of the Endurance, crushed by tightening pack ice This image shows idealised cross-sections of early Antarctic ships. Thick arrows represent compressive ice load. Endurance, Discovery, Belgica, Scotia, and Aurora, were of type A; Fram, Gauss and Deutschland were of type B. Note the diagonal beams for extra strength in B What happened to Endurance? First launched in 1912, Endurance has long been seen as emblematic of the heroic age of Antarctic exploration.In August 1914, ship owner Sir Ernest Shackleton and his crew set out in Endurance to achieve the first land crossing of Antarctica.Sadly, Endurance did not reach land and became trapped in dense pack ice the following year, forcing the 28 men on board to eventually abandon ship.Shackleton died on another expedition in 1922, while Endurance wasn't found on the ocean floor for another century. More than 100 years later, the tearing off of the ship's rudder by ice is still given as the sole cause for the sinking of Endurance or its 'Achilles' heel', but this is not supported by written evidence. Amazingly, Shackleton's diaries, personal correspondence and other communications shows he knew about the ship's weaknesses. 'We really have to wonder why Shackleton chose a vessel that was not strengthened for compressive ice,' Professor Tuhkuri said. 'Before he set off he lamented the ship's weaknesses in a letter to his wife, saying he'd exchange Endurance for his previous ship any day,' he said. 'In fact, he had recommended diagonal beams for another polar ship when visiting a Norwegian shipyard. 'That same ship got stuck in compression ice for months and survived it.' There has long been a popular narrative that Endurance was the strongest wooden ship of its time, only let down by its the rudder. But the study, published in the journal Polar Record, concludes these assumptions are not supported by evidence. Endurance in full sail in the ice during the Imperial Trans Antarctic Expedition - when it met its downfall. The wreck of Endurance is now designated as a protected historic site and monument under the Antarctic Treaty Ernest H. Shackleton (1874 - 1922) during the Imperial Trans-Antarctic Expedition in which the Endurance sank. Endurance was not among the strongest ships of its time, nor was the rudder the main cause of the vessel sinking, this study claims Endurance was nipped by ice on 24 October 1915, as recorded here in the diary of Frank Worsley, Endurance's captain Endurance: Key stats Type: Three-masted schooner barqueFormer name: Polaris* Builder: Framnæs shipyards, Norway Launched: December 17, 1912 Crew complement: 28 Length: 144 feet (44 metres) Beam: 25 feet (7.6 metres) Tonnage: 348 register tons Propulsion: Steam and sail Max. speed: 10.2 knots (11.7 mph)Sank: Weddell Sea, November 21, 1915 Notable features: Strengthened hull and denser framework custom-designed for polar waters 'While the final reason was tearing off the keel, Endurance sank because the vessel was simply crushed in compression by ice,' said the expert. 'This is not surprising; Endurance was not designed for compressive conditions in the Antarctic pack ice, but for easier conditions at the ice edge in the Arctic.' Exactly why the explorer chose to sail into the dangerous Antarctic ice pack aboard Endurance at all is now the 'key question', although one possible theory is that Shackleton was just dedicated to getting the job done. 'My feeling is he understood that if you want to get something done, you need to start taking steps towards the goal,' Professor Tuhkuri told the Daily Mail. 'If you plan too long or think too much, you may end up staying at home – I think we all recognise that in our own lives. 'Maybe Endurance was the best ship available with the money he had and in this time frame. I would have used much more time for the preparations, but Shackleton had a different way of working.' It's also clear that due to his nature Shackleton 'was ready to take risks' and trusted himself that he could solve problems if they materialised. If this is the case, Shackleton was right – because all 28 men on board survived the sinking. 'We know that this really was the case – he got all his men back home,' said the expert. 'In addition, he was always optimistic – it was his philosophy to stay optimistic whatever happens.' The taffrail, ship's wheel and aft well deck on the wreck of Endurance, Sir Ernest Shackleton's ship, which has been found 100 years after Shackleton's death Endurance (pictured) sank in November 1915 after becoming trapped in sea ice off the coast of Antarctica. The wreck was lost for over 100 years until its discovery in 2022 Six years after the Endurance sank, Shackleton led the Quest expedition to circumnavigate the Antarctic continent. Just before Quest left Rio de Janeiro for the sub-Antarctic island of South Georgia, Shackleton suffered a suspected heart attack but declared himself better the next morning. Read More Incredible 3D scans reveal Ernest Shackleton's ship Endurance as it was before it sank However, during the two-week voyage, Shackleton was seen to drink heavily to deaden the pain he was in, namely with champagne. Dr Alexander Macklin, who was on watch on the evening of January 5, 1922, had visited Shackleton in his cabin.After encouraging Shackleton to take things easy, Macklin was rebuked with the words: …'You always want me to give up something. What do you want me to give up now?'Macklin replied: 'Chiefly alcohol, Boss, I don't think it agrees with you.'Soon afterwards Shackleton had a very severe intensification of symptoms, during which he died, just after its arrival at South Georgia. Sir Ernest Shackleton: Famed Anglo-Irish Antarctic adventurer Sir Ernest Shackleton during the 1908 expedition to AntarcticaSir Ernest Henry Shackleton was an Anglo-Irish Antarctic explorer who led three expeditions to the frozen continent. He was at the heart of a period in history that later came to be known as the 'Heroic Age of Antarctic Exploration'.Born in Ireland, Shackleton moved to London with his family when he was 10 and first experienced polar climates as an officer on Captain Robert Falcon Scott's Discovery expedition of 1901–1904.He was sent home early from that expedition after work experiencing poor health that had been ascribed to scurvy. New studies suggest he had beriberi. During the Nimrod expedition of 1907–1909, Shackleton and his companions created a new recorded of farthest south latitude at 88 degrees south. Disaster struck his next expedition, the Imperial Trans-Antarctic Expedition, 1914–1917, when the ship, the Endurance, became trapped in pack ice.The crew were able to escape by launching lifeboats and reaching nearby islands, travelling through stormy oceans for 830 miles.He returned to the Antarctic for one final time in 1921 with the Shackleton–Rowett Expedition, but died of a heart attack on January 5, 1922, while his ship was moored in South Georgia. While Shackleton is best known for his exploration, his legacy is also one of enabling a considerable amount of scientific research. His expeditions helped produce comprehensive scientific and geographical surveys — among which were the first surveys of Antarctica's interior and the effective location of the Magnetic South Pole.'Shackleton is an iconic figure of Antarctic history with the most incredible legacy of courage and endeavour,' noted the UK Antarctic Heritage Trust's CEO, Camilla Nichol.'But we sometimes overlook the contribution his expeditions made to science.'To this day Antarctica is an essential barometer for climate change at the heart of climate science. 'We preserve Shackleton's legacy to inspire the next generation of pioneering scientists and explorers.'
