Shackleton’s Endurance: New Research Challenges Ship’s Legendary Strength

A new scientific investigation is challenging long-held assumptions about Sir Ernest Shackleton’s ship, Endurance, suggesting the vessel may not have been as well-suited for the extreme Antarctic conditions it faced as previously believed. The Endurance, famously crushed by sea ice and sinking in November 1915, has long been considered a remarkably strong polar ship, though thought to have a critical flaw in its rudder.

Rethinking the Endurance’s Design

The study, published in Polar Record on October 6, 2025, is the first to combine engineering analysis with detailed reviews of diaries and letters from the expedition. Researchers suggest the ship had multiple structural shortcomings that made it less durable than other early polar vessels.

“Even simple structural analysis shows that the ship was not designed for the compressive pack ice conditions that eventually sank it,” says Jukka Tuhkuri, a professor of solid mechanics at Aalto University and a leading ice researcher. “The danger of moving ice and compressive loads—and how to design a ship for such conditions—was well understood before the ship sailed south. So we really have to wonder why Shackleton chose a vessel that was not strengthened for compressive ice.”

Structural Weaknesses Identified

Tuhkuri, who participated in the Endurance22 mission that located the wreck in 2022, was surprised that no thorough structural assessment had been done previously. His investigation revealed several structural deficiencies compared to other early Antarctic ships:

• Weaker deck beams and frames
• A longer machine compartment, weakening a significant part of the hull
• The absence of diagonal beams to strengthen the hull

“Endurance clearly had several structural deficiencies compared with other early Antarctic ships,” Tuhkuri explains. “Not only does this challenge the romantic narrative that it was the strongest polar ship of its time, but it similarly belies the simplistic idea that the rudder was the ship’s Achilles’ heel.”

Shackleton’s Awareness of the Ship’s Limitations

Reviewing Shackleton’s diaries, personal letters and crew communications, Tuhkuri found evidence suggesting Shackleton was aware of the ship’s weaknesses before the expedition departed. “Shackleton knew about this. 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. 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,” says Tuhkuri.

Human Choices and the Fate of the Endurance

The study does not aim to diminish the achievements of Shackleton and his crew, but rather to offer a more detailed understanding of the circumstances surrounding the ship’s loss. The question remains whether the Endurance was simply “ill-fated,” or if human choices played a larger role in its demise.

“We can speculate about financial pressures or time constraints, but the truth is we may never know why Shackleton made the choices that he made. At least now we have more concrete findings to flesh out the stories,” Tuhkuri concludes.

About the Endurance

Endurance was a three-masted barquentine built in 1912 at Framnæs shipyard in Sandefjord, Norway. Originally named Polaris, the ship was purchased by Shackleton in 1914 for the Imperial Trans-Antarctic Expedition. The ship became trapped in pack ice in 1915 and sank on November 21, 1915, at coordinates 75°23′S 42°14′W. The wreck was discovered on March 5, 2022, in the Weddell Sea at 68°44′21″S 52°19′47″W. Learn more about the Endurance.