What It Took To Discover the Endurance

Based on what I learned during my long Antarctic deployment with the US Coast Guard aboard the USCGC Glacier, as well as the subsequent research I did prior to writing my nonfiction book, Wind, Fire, and Ice, I seriously doubted the Endurance would ever be discovered. The main reason was because of prevailing ice conditions in the Weddell Sea, an area often referred to as “The Cold Factory of Antarctica”. It has been the graveyard of many ships, particularly during the “Heroic Age” of Antarctic exploration (1898 to 1922).

            During modern times, the Weddell Sea put even heavy-duty icebreakers in serious peril. In 1970 the USCGC Glacier, at the time the biggest icebreaker in the free world, was beset within 70 miles of where the Endurance was first trapped. In 1984 the USCGC Westwind barely escaped destruction when it was pinned against the massive Larsen Ice Shelf. The historian, Thomas R Henry, wrote in his 1950 book, The White Continent, “The Weddell Sea is, according to the testimony of all who sailed through its berg-filled waters, the most treacherous and dismal region on earth.”

In 1823, British sailor James Weddell discovered the sea later named after him and found it relatively ice free, so much so that he was able to sail to 74° South. That furthest-south record stood for over a century. The feat was so unusual that William Herbert Hobbs, geologist, and author of the article entitled, “The Pack-Ice of the Weddell Sea”, accused Weddell of being “a fake explorer”. Hobbs should have focused more on what typically happened to other early explorers, like the French explore, J. S. C. Dumont d’Urville , or the American explorer, Charles Wilkes. Neither were able to penetrate the Weddell Sea. The Norwegian skipper, Carl Anton Larsen, successfully sailed into the northern portion of the Weddell Sea in 1902, but the following year his ship, Antarctic, was crushed and sank when he attempted another voyage into the Weddell Sea. The same thing almost happened to Weddell in 1824, t when his ship, the Jane, failed to penetrate the heavy ice on the edge of the Weddell Sea, struck an iceberg, an came close to sinking.

Although the Weddell Sea as a whole is treacherous, its western edge, where the Endurance sank, is generally impossible to navigate. It is because the normal current pattern or gyre in the Weddell Sea forces ice against the eastern side of the Antarctic Peninsula. The ice there is invariably composed of multi-year ice—ice that formed in previous years but did not melt during the summer season. Salt leaches out of this older ice, creating something more like glacial ice, known to have the tensile strength of steel. Moreover, the violent storms typical in the Weddell Sea pile this multiyear ice into tall ridges, often 15 to 20 feet high. As a result, this part of the Weddell Sea is generally considered impassable, by even the biggest icebreakers, at any time of the year. Shackleton described the area as,“the worst portion of the worst sea on earth.”

            Most icebreakers are built to primarily handle sea ice created that same year. This kind of ice is softer and usually not too thick. The average icebreaker can plow through surface sea ice two to three feet thick without much of a problem. Heavier duty icebreakers can push through sea ice three to five feet thick. Using “back in and ramming” techniques, the heaviest duty icebreakers, like the Glacier are capable of busting through sections of ice up to 20 feet thick, but they’re not built for pounding through ice that thick day after day. Work like that requires tons of fuel and is more likely to damage the ship. Even though the Glacier was the most powerful icebreaker in the free world for many years, it invariably ended up in dry dock for repairs after each Antarctic deployment because of the beating it took.

According to an article in the spring issue of Wreck Watch Magazine, Mensun Bound, a renowned maritime archaeologist, first toyed with the idea of searching for the Endurance back in 2012. A fifth -generation Falkland Islander, Bound had been running successful deep-sea projects since the 1980s. He grew up in a community of 2000 people totally dependent on shipping for their survival, as well as an area rich in nautical history. Many of the clipper ships incapable of beating through the winds and currents around Cape Horn, sailed back to the Falklands and ended up as un-seaworthy wrecks in the local harbors.

According to Bound, essentially everyone on the island was a Shackleton enthusiast. In fact, his great-great-Uncle, Vincent Biggs, ran a bar and boardinghouse where Shackleton and Frank Worsley once stayed (and the notoriously cash-strapped explorer left with a balance due.)

Back in 2012, the Natural History Museum asked Bound to consider getting involved in a project to find the wreck of the Terra Nova, the ship that carried Scott on his last expedition in 1910. Before Bound had much of a chance to consider the offer, he was shocked to learn that the wreck had been located by another group. A friend then suggested, “Well, what about the Endurance?”

At the time, Bound considered the Endurance the “most unreachable wreck in the world.” He could not imagine finding an icebreaker capable of smashing through one hundred miles of ice, fifteen feet thick in many places, to even begin reaching the search area. In addition, he did not think the technology of AUVs (autonomous underwater vehicles) was yet sufficiently advanced. But the germ of the idea had been firmly planted.

By 2017, Bound believed the AUV technology had advanced enough to seriously consider searching for the famous wreck. His friend, John Kingsford from Deep Ocean Search, was given the task of finding a capable icebreaker. Subsequently, they were joined by Donald Lamont, ex-Governor of the Falkland Islands, George Horsington, a shipping specialist, and John Shears, a logistics specialist with the British Antarctic Survey. Funding was provided by the Flotilla Foundation, a registered charity focusing on marine ecology.

The first attempt to locate the Endurance began in 2019. Bound described the search as “more challenging than anything I’ve ever known in my long career in maritime archaeology.” After all, they were headed for an area Bound described as “old, gnarled, multiyear ice …very thick and virtually impenetrable,” in other words, normal conditions for that stretch of the Weddell Sea.

The S.A. Agulhas II, a South African icebreaker was selected for the mission, led by Captain Freddie Lighthelm and master ice pilot, Knowledge Bengu. Although very experienced, the duo had not previously sailed in the proposed search area. Before they could even get close, the 440-foot-long vessel had to resort to “backing and ramming” techniques to plow through the ice. Despite these efforts, the ship became stuck in the ice for several days. At one point it was “nipped” between two huge ice floes. Captain Lighthelm said, “At the nipping/connecting point, I could feel the vibration of the ship as it squeezed the hull, and I could then imagine how Endurance was crushed.”

The skipper constantly worried that massive chunks of ice might damage the props. He added, “my biggest fear would be to suffer mechanical damages whilst in the Weddell Sea,” given that there would not be any other ships around that could provide assistance. One of the crewmembers calculated that the nearest humans beyond the ship were in the International Space Station.  

By the time they reached the most likely area to find the wreck, Bound and his team were limited to only 50 hours of bottom time for the AUV’s to scan and search. (The ship had another urgent mission—to relieve scientists on the Antarctic continent before winter set in.)  Unfortunately, Bound and his team could only deploy one of the AUV’s because the electronics capsules on the only other one had earlier “imploded”. The functioning AUV started out its search pattern without any difficulties. However, about twenty hours later they lost contact. It could have been carried away by current or sunk to the bottom. Bound thought the most likely explanation was that it, “self-aborted its mission and returned to the surface.” Normally, this would not have been a problem, because the unit would have established satellite contact as soon as it surfaced, but not if it was stuck underneath the icepack, which likely was the case. Bound concluded, “Anyway you look at, the 2019 search to find the Endurance was a fiasco.”

Bound and his team viewed the “devastating” failure of the 2019 expedition as being “a big learning process.” However, they shouldn’t have been that hard on themselves, given that the odds were stacked against them. The results were about what one would expect. At least they were able to escape without getting trapped.

 The team subsequently thought they would have better luck with newer technology, specifically an improved Sabertooth vehicle manufactured by SAAB. The new AUV was designed to operate in both an autonomous mode and via a fiber-optic cable tethered to the surface. This combination allowed them to constantly monitor its location so that a second AUV could be sent to rescue it if necessary.

No doubt inspired in part by Shackleton’s motto, “By Endurance We Conquer,” Bound and John Shears began to form a group for Endurance22. The Falklands Maritime Heritage Trust was given overall control of the new campaign. Bill Featherstone, Saul Pitaluga, and Bound became the Trustees. Overall leadership was again provided by Donald Lamont, Chairman of the Trust. The subsea team was headed by Nico Vincent and his deputy, J. C. Caillens. 

On February 6th, 2022, the Endurance22 expedition set off from Cape Town aboard the S.A. Agulhas II.  Unlike 2019, the mission had a much better chance of success because of strikingly different ice conditions. A shift in the current had forced most of the multiyear ice towards the distant eastern edge of the Weddell Sea. The icebreaker was able to cruise at five knots through soft, first-year sea ice with relative ease. However, even with remarkably good conditions, they got stuck in the icepack for a day.

Once the ship reached the search area—one closely correlated with the coordinates Frank Worsley, captain of the Endurance, had determined when the vessel sank 107 years earlier— the team launched the sophisticated Sabertooth AUV’s. This time the equipment problems were not with the multi-million-dollar AUV’s but with the new on-deck winch system. When pulling the AUV’s back onto the ship, sea water coating the tether cables froze so quickly that it was hard to spool the cables onto the winch drums. The winches struggled to maintain proper tension on the cables, which contributed to them getting pinched and rupturing the delicate fiber optics in the cables. Fortunately, Nico Vincent had decided to bring a less sophisticated, 25-year-old winch system as a backup. The old winch did the job.

With temperatures dropping to minus 35 degrees centigrade, it was difficult and dangerous work for the sub-sea team. Frostbite was a constant concern.  Sometimes it was so cold their tears would freeze their eyes shut.

The Sabretooth AUV’s were set to travel in a systematic search grid that covered portions of an 130 square mile area. For days they scanned the ocean bottom and found nothing.  They were running out of time.

Towards the end of their mission, with only eight hours of search time left, the AUV picked up an image of something on the seafloor that looked promising. The data cascade revealed something three to four meters high. Every other potentially interesting image they had picked up had been essentially flat.

            However, the AUV batteries had run down. They had to abort the search.

            After charging the batteries, the search resumed. The Sabertooth returned to the promising area in order to conduct a low-altitude pass.

 A high-frequency, high- resolution sonar scan produced a definitive image.

            The Endurance was discovered the afternoon of March 5, 2022, exactly 100 years after Shackleton had been buried on South Georgia Island. It was located at 58° 39’ S.  052° 26” W, lying proudly upright on the seabed, 10,000 feet below the surface, approximately 4 miles south of the position last recorded by Captain Worsley.

            Bound and John Shears were hiking to an iceberg frozen into the icepack when the discovery occurred. When they returned to the ship, they were told to urgently report to the bridge. Fearing something serious had happened, like the loss of a Sabertooth, they rushed to the bridge. When they arrived, Nico Vincent pushed a camera towards them showing a high-resolution image and said, “Gents, let me introduce you to the Endurance.” The entire ship broke into cheers. Upon hearing the news Bound said, “I felt the breath of Shackleton on my neck.”

            Prior to the discovery, Bound had predicted that the wreck would be well preserved because of the absence of destructive ship worms and marine parasites in the frigid waters of the Weddell Sea. (His prediction was spot on. The image that struck him the most was when he first saw the ship’s name across the stern, as well as the ship’s wheel standing upright. He added, “I was gob smacked by the clarity and detail of the Endurance’s preservation. You could even see its paintwork, count the spokes of the steering wheel, and read the dial on the sounding apparatus.”

Bound also predicted that the ship would be largely intact. He knew from the building plans of the Endurancethat it was one of the strongest wooden ships ever built, plus none of the crewmembers had ever claimed that the ship, although badly damaged, had ever been completely crushed. In contrast, Bound noted that less well constructed wooden ships containing auxiliary power would normally break apart around the engine room or boiler room upon impact with the seafloor.

Although some of the things lying on the outer deck could have been retrieved, like the ship’s bell or one of Frank Wild’s boots, nothing was touched. Instead, the ship was videoed and photographed in minute, 3D detail.

When the 25,000 plus photos have been processed and analyzed, then synched with the ship’s plans, it will be possible to have virtual reality tours of the ship.

 Per the Antarctic Treaty, the ship will remain pristine and undisturbed, but it will become part of the metaverse, where it will be possible for anyone anywhere to walk its decks and explore every aspect.

According to Alexandra Shackleton, the explorer’s granddaughter, she was once asked to define the qualities necessary for a polar explorer. She said, “First optimism, then patience, imagination and finally courage”. Bound and his team needed all these qualities, as well as a bit of luck, in their quest to find the Endurance. Bravo to them for achieving a discovery long thought to be impossible.

Following the discovery, Bound posted, “This is a milestone in polar history. However, it is not all about the past; we are bringing the story of Shackleton and Endurance to new audiences, and to the next generation, who will be entrusted with the essential safeguarding of our polar regions and our planet. We hope our discovery will engage young people and inspire them with the pioneering spirit, courage, and fortitude of those who sailed Endurance to Antarctica.”