More than a century after it struck an iceberg and sank beneath the waves, the Royal Mail Ship Titanic continues to capture the popular imagination. It is a classic fable of ambition, hubris, and the tragic social divisions of the Gilded Age, and has inspired countless books, documentaries, TV programs, and one of the highest-grossing feature films of all time. But while the memory of the Titanic lives on, for more than seven decades the ship itself remained lost, hidden somewhere beneath the vast North Atlantic. Then, on September 2, 1985, an expedition by oceanographer Dr. Robert Ballard finally discovered the wreck at a depth of nearly four kilometres, reigniting a global obsession with the ship and her sinking that persists to this day. However, this discovery very nearly didn’t happen at all, for Ballard did not initially set out to find the Titanic. His historic 1985 expedition was actually part of a secret U.S. Navy mission to survey the wrecks of two sunken nuclear submarines, the loss of which remains one of the greatest mysteries of the Cold War.

The nuclear fast attack submarine USS Thresher was launched on July 9, 1960 from Portsmouth Naval Shipyard in Maine. The lead boat in her class, the 85-metre-long, 3,200-ton Thresher was the most capable and technologically-advanced submarine in the U.S. Navy to date – so advanced, in fact, that shortly after her launch the Navy approved the construction of 14 more of the same class – an unprecedented order in U.S. naval history. Designed to hunt down and destroy Soviet ballistic missile submarines, Thresher could reach speeds of up to 33 knots and depths of 500 metres, and was fitted with the latest electronic systems and weapons, including the SUBROC nuclear-tipped antisubmarine missile. As the first of her class, Thresher spent much of her early career undergoing extensive sea trials and tactical exercises to evaluate her performance and advanced onboard systems. On July 16, 1962, she entered the Portsmouth dry dock for a thorough inspection and overhaul, returning to service on April 8, 1963.

On April 9, as part of her post-overhaul evaluation, Thresher sailed to a position 350 kilometres east of Cape Cod to meet up with the submarine rescue ship Skylark and conduct deep-diving trials. After making two preliminary dives to half test depth, at 6:30 the following morning Thresher began the test proper. Sailing in large circles beneath Skylark to remain within hydrophone communication range, Thresher slowly descended, pausing every 30 metres to check the integrity of her systems before continuing the dive. At first all went well, but at 9:18 AM, as Thresher approached her test depth, the crew of the Skylark received a garbled message from the submarine:

” …  minor difficulties, have positive up-angle, attempting to blow, will keep you informed…”

This was followed by a second, even more garbled message…then nothing. Skylark desperately attempted to reestablish contact with the submarine, but the minutes ticked past in silence, the grim realization slowly dawned on everyone aboard: USS Thresher had been lost, along with all 129 of her crew. It was the second greatest disaster in the history of submarine warfare and the worst to involve a nuclear submarine.

News of Thresher’s loss shocked the American public, and as President John F. Kennedy ordered flags flown half-mast across the country, a massive expedition was launched to locate the wreck and determine the cause of the sinking. The recovery fleet included the advanced sonar ship NRL Rockville, the oceanographic vessel USNS Mizar, and even the deep-diving bathyscaphe Trieste, which on January 23, 1960 had become the first manned vessel to reach the bottom of the Marianas Trench, the deepest point on earth. After more than a month of searching using camera sleds towed along the seabed, the main body of the wreck was finally located on June 27, 1963 at a depth of 2,500 metres. What the cameras revealed was shocking: Thresher had been completely ripped apart, its hull lying in six large pieces amid a debris field covering some 134,000 square metres. The investigators were baffled as to what could have caused such catastrophic damage.

Over the next month the search expedition managed to photograph the majority of the debris field, and based on these photographs, debris recovered from the seafloor, and an examination of the Thresher’s design, a clearer picture of the events of April 10 began to take shape. The official board of inquiry concluded that as Thresher approached test depth, she had likely suffered a failure in her salt-water piping system, which made extensive use of silver brazing instead of conventional welding. A similar failure had occurred on November 30, 1960 aboard the submarine USS Barbel, causing nearly 18 tons of water to flood into her engine room before she was able to blow her ballast tanks and surface. Had such a failure occurred aboard Thresher, the water could have shorted out vital circuits and triggered an automatic shutdown or “scram” of her reactor. As nuclear submarines rely mainly on propulsion and dive planes for diving and surfacing and only blow their ballast tanks near the surface, such a shutdown would have left Thresher dead in the water. And while standard procedure would have been to order an emergency blow of the ballast tanks, experiments conducted aboard Thresher’s sister ship USS Tinosa revealed that the sudden release of pressure from the air flasks could cause the release valves to freeze and clog up with ice, preventing further air from reaching the ballast tanks. Thresher thus helplessly plunged deeper and deeper until, at a depth of around 700 metres, the immense water pressure caused her to implode, ripping her hull apart like a tin can.

In the wake of the Thresher disaster, the Navy launched SUBSAFE, a quality-assurance program that ensured that every component exposed to water pressure met strict material and manufacturing standards. The Navy hoped SUBSAFE would prevent a repeat of the Thresher tragedy, and for a while it seemed to work. But then, in early 1968, disaster once again struck the nuclear submarine fleet.

On May 21, 1968, the Skipjack-class fast attack submarine USS Scorpion was crossing the Atlantic, returning to its home port of Norfolk, Virginia from the Azores. For the past two months Scorpion had been posted to the Mediterranean, where she had acted as an aggressor in NATO antisubmarine exercises. Launched on December 29, 1959, by 1968 Scorpion was beginning to show her age. Suffering from a litany of mechanical problems including hydraulic leaks, excessive vibration, seawater leaks around her propeller shaft, and ballast tank problems that limited her maximum depth to only 100 feet, she was badly due for an overhaul. However, Navy budget constraints and Cold War pressures continually delayed much-needed repairs. These delays were a constant source of frustration for the crew, with several demanding to be transferred off what they referred to “USS Scrap Iron.”

In late April 1968 Scorpion was preparing to leave Naples for Norfolk when she received a message ordering her to make for the Azores instead. Unusual Soviet naval activity had been spotted in the area, and Scorpion was instructed to observe and report. Scorpion discovered two November-class fast attack submarines and a missile cruiser operating just south of the Azores, but after watching them through her periscope for three days observed nothing unusual and headed home at a speed of 18 knots. On May 21, Scorpion sent a radio message announcing she would arrive in Norfolk on May 27 at 1PM.

May 27 came and went, yet Scorpion did not arrive. At first there was little cause for concern; submarines were delayed all the time. But as days and then weeks passed, the Navy began to fear that something had gone terribly wrong. Finally, on June 5, two weeks after Scorpion was due back in Norfolk, the submarine and her 99 crew were declared “missing, presumed lost.” Scorpion was one of four submarines lost under mysterious circumstances in 1968, along with the Israeli Dakar, French Minerve, and Soviet K-129, the latter of which was partially recovered in a secret CIA operation called Project Azorian in 1974.

Speculation as to the cause of Scorpion’s loss ran wild, with many suspecting she had been sunk by the very Soviet vessels she had been ordered to spy on. Yet no unusual naval activity had been observed either before or after Scorpion’s disappearance. The only way of determining her true fate was to locate the wreck. However, unlike with the Thresher, the Navy had little idea of where the Scorpion might have sunk, making the chances of finding her exceedingly remote. Fortunately they had an ace up their sleeve: a man with unique experience in just this kind of search operation. The former head of the Navy’s Special Projects Office, John P. Craven had made his name in 1966 when, on January 17, a Strategic Air Command B-52 bomber collided with a KC-135 aerial tanker and broke apart over Palomares, Spain, resulting in a 1.1-megaton B28 thermonuclear bomb falling into the Mediterranean. Standard Navy search procedure would have been to divide a large search area into grid squares and have ships, submersibles, and towed camera sleds methodically sail back-and-forth across each square, a process known as “mowing the lawn.” However, Craven decided to take a more analytical approach, and developed a novel search method based on a branch of mathematics known as Bayesian Probability. Based on factors such as the speed, course, and altitude of the aircraft and a sighting by a Spanish fisherman of the bomb entering the water, Craven assigned each grid square a different probability, which was continuously updated as the search progressed. This method significantly reduced the search time, and on March 17, 80 days after the crash, the bomb was successfully recovered by the submersible Alvin at a depth of 780 metres.

But in order to apply his method to the search for Scorpion, Craven needed more data. If Scorpion had sunk not long after her final transmission, Craven reasoned, then she would have quickly reached her crush depth and imploded, creating a distinctive sound that could be detected by underwater hydrophones. At first Craven turned to the Navy’s Sound Surveillance System or SOSUS network, but this was designed to detect the engine noise of Soviet submarines and filtered out louder sounds like explosions. However, Craven managed to to locate a research hydrophone in the Canary Islands and two more in Newfoundland, and after digging through reams of data printouts finally found what he was looking for: a pair of loud explosions, ninety seconds apart, at around the same time Scorpion was thought to have disappeared. While the first explosion was a mystery, the second was most likely the sound of Scorpion imploding. By triangulating the signals from all three hydrophones, Craven was able to narrow the search area to a much more manageable size. But he had also turned up an unexpected fact: while everyone had assumed Scorpion was heading west when she sank, the hydrophone data revealed that she was actually heading east, back towards the Mediterranean. When Craven asked submarine commanders what this could possibly mean, the answer was unanimous: Scorpion had suffered a “hot run.”

Among a submariner’s worst nightmares is to be hit by one’s own torpedo. For this reason, torpedoes are fitted with a safety mechanism that disarms them if they turn past 180 degrees. If a submarine experiences a “hot run” – Navy jargon for a torpedo accidentally arming in its tube – standard procedure is to turn the submarine around in order to trigger this mechanism and prevent the warhead from detonating. Indeed, Scorpion had survived just such an incident only 6 months before.The hydrophone data seemed to indicate this time she had not been so lucky, and that she had either been struck by her own torpedo or a torpedo had accidentally exploded in its tube, flooding the forward compartment and sending the submarine plunging to the bottom. To support his theory, Craven conducted a computer simulation with Scorpion’s former executive officer, Lieutenant Commander Robert Fountain, in which Craven simulated a hot run and an explosion in the torpedo compartment. Despite Fountain’s best efforts to save his ship, the submarine quickly sank and reached crush depth after 90 seconds – exactly like in the hydrophone data. Years later, Craven would discover that the Mark 46 silver-zinc batteries used on the Mark 37 torpedo had a disturbing habit of bursting into flames and exploding during vibration tests, and that such fires were hot enough to potentially set off the torpedo’s warhead. In fact, the report announcing this flaw had been published shortly before Scorpion’s disappearance, but once again due to budgetary constraints the Navy ignored it and refused to overhaul its torpedoes.

Though the Navy was initially skeptical of Craven’s claims that Scorpion was heading east at the time of her sinking, they nonetheless allowed him to proceed with his search, and on October 29, 1968 the survey ship USNS Mizar finally located the wreck at a depth of 3,000 metres – less than an eighth of a mile from where Craven predicted it would be. Shortly thereafter, the Navy bathyscaphe Trieste II was sent down to survey and photograph the wreck. Trieste II discovered that Scorpion had impacted the seafloor at high speed, digging a long trench in the mud, and that her centre section containing her control room had completely imploded, detaching her sail and splitting the wreck into two pieces. However, photographs revealed no evidence of damage to the torpedo compartment, either from an external hit or an internal explosion. Consequently, the 1969 board of inquiry concluded that no incontrovertible proof could be found for the cause of the sinking. The exact circumstances of Scorpion’s loss remain a mystery to this day.

But while the Navy had officially closed the book on Thresher and Scorpion, they was not quite finished with the two submarines. As both were nuclear powered, it was feared that their reactors might leak radioactive contamination into the surrounding environment, forcing the Navy to carry out a pair of monitoring expeditions in 1965 and 1977 to sample water and sediment around the wrecks.  In the 1980s, the behaviour of reactors in the deep ocean became particularly topical as the U.S. Navy considered disposing of surplus nuclear submarines at sea to comply with the SALT arms-limitations treaties. And it is here that Robert Ballard enters the picture.

Ballard had long been obsessed with finding the wreck of the Titanic, and he wasn’t alone. Soon after the sinking, the families of some of the ship’s wealthier victims such as John Jacob Astor and Benjamin Guggenheim contracted the Merritt and Chapman Derrick and Wrecking Company to salvage the Titanic. However, this project was quickly abandoned as the wreck lay far beyond the reach of contemporary diving technology. Over the following decades dozens of harebrained schemes would be proposed for raising the Titanic, including filling the wreck with ping-pong balls, vaseline, or ice to float her to the surface, but none of these plans went anywhere due to technological and financial constraints and the simple fact that nobody was quite sure were the Titanic had actually sunk. In 1977, while working for the Woods Hole Oceaographic Institute in Massachusetts, Ballard launched his first privately-funded expedition to locate the wreck. Sailing aboard Alcoa aluminium company’s drillship SeaProbe, Ballard used a camera rig attached to a long drill pipe to scour the ocean floor. Unfortunately, the expedition ended in disaster when the drill pipe broke, sending the modern equivalent of $2 million dollars worth of camera equipment plunging to the ocean floor. Despite this, Ballard was confident that with better technology the Titanic would eventually be found. Back at Woods Hole, Ballard used Navy funding to develop a pair of advanced remotely operated vehicles or ROVs to explore the ocean floor: Argo, a towed camera sled; and Jason, a fully mobile robotic submersible that could be controlled from the surface. In 1982 Ballard approached the Navy to fund an expedition to locate the wreck of the Titanic. While the the Navy was initially uninterested, they eventually recognized that Argo and Jason could be used to conduct a more thorough survey of USS Thresher and Scorpion, potentially allowing the true causes of the sinkings to be determined. They then further realized that one mission would form the perfect cover story for the other, and that Ballard – a former Navy officer himself – could be given the security clearance needed to examine the submarines. Both sides thus reached a compromise: the Navy agreed to fund Ballard’s expedition, on the condition that he survey the wrecks of Thresher and Scorpion first. Any remaining time could then be used to search for Titanic. As Ballard later recalled:

“We knew where the subs were What they wanted me to do was go back and not have the Russians follow me, because we were interested in the nuclear weapons that were on the Scorpion and also what the nuclear reactors were doing to the environment.”

Ballard set out on his first expedition to photograph USS Thresher in the summer of 1984, sailing aboard the Woods Hole research vessel RV Knorr. This was followed the following summer by a second voyage to photograph Scorpion off the Azores. In both cases Ballard sailed under the guise of searching for the Titanic, and was forbidden from revealing the true purpose of the mission:

“I couldn’t tell anybody. There was a lot of pressure on me. It was a secret mission. I felt it was a fair exchange for getting a chance to look for the Titanic. We handed the data to the experts. They never told us what they concluded – our job was to collect the data. I can only talk about it now because it has been declassified.”

Knowing that the official expedition schedule would leave him little time to search for the Titanic, Ballard partnered with the French Research Institute for the Exploration of the Sea. While Ballard and the Knorr surveyed the Scorpion, the French research vessel Le Suroit sailed ahead to scout the Titanic search area, using a towed side-scan sonar array to survey a 390-square-kilometre area of seafloor for large metallic objects. The idea was for Le Suroit to locate potential targets, which Knorr would later investigate using Argo. However, despite five weeks of searching, Le Suroit came up empty-handed and the ship was recalled to France. Ballard, having just finished photographing the Scorpion, now had only 12 days to find the Titanic on his own.

Thankfully, the expeditions to Thresher and Scorpion had provided Ballard with a valuable insight. Both submarines had broken apart as they sank, scattering debris over a wide area of seafloor. Due to ocean currents these debris fields took the form of a large fan like the tail of a comet, with the larger, heavier pieces falling close to the main wreck and smaller, lighter objects farther away. Ballard realized that the sinking of the Titanic would likely have created a similar debris field, creating a much larger and easier-to-find target than the wreck itself. And while sonar could not distinguish man-made objects from natural ones, the human eye could. So instead of repeating Le Suroit’s sonar survey, Ballard decided to sweep the ocean floor with Argo and follow the debris field to its source. For nearly a week the Knorr sailed-back and-forth across the search areas, with multiple shifts monitoring Argo’s cameras 24 hours a day. Day after day the cameras returned nothing but featureless mud, and as the 12 day allotment drew to a close Ballard began to fear he had failed once again. But then, in the early morning hours of September 1, 1985, a large object appeared on the monitor: it was a marine boiler, identical to those installed aboard Titanic. The next day at 2:20 AM – the exact time the Titanic sank – the ship’s streamlined bow drifted into view. A cheer erupted among the crew: after 73 years, the Titanic had finally been found. However, the jubilant mood quickly faded as the full weight of the discovery hit:

“We realized we were dancing on someone’s grave, and we were embarrassed. The mood, it was like someone took a wall switch and went click. And we became sober, calm, respectful, and we made a promise to never take anything from that ship, and to treat it with great respect.”

The rediscovery of the Titanic made headlines around the world and turned Ballard into an instant celebrity – much to the Navy’s chagrin:

“…the Navy never expected me to find the Titanic, and so when that happened, they got really nervous because of the publicity. But people were so focused on the legend of the Titanic they never connected the dots.”

It was not until 2018 that the mission was declassified and Ballard was allowed to reveal the military connection to his greatest discovery. Ballard has since admitted that he has participated in numerous other secret Navy missions, but cannot discuss them until they, too, are officially declassified.

In 1986, Ballard returned to Titanic with the deep-diving submersible Alvin, and became the first person to set eyes upon the ship in nearly three-quarters of a century. This expedition revealed a number of unexpected details regarding the ship and her sinking. While most historians up until that point believed that Titanic had sunk in one piece, Ballard discovered the wreck in two pieces lying 600 metres apart. This supported the assertion of many eyewitnesses that as Titanic sank by the bow, her stern rose free of the water and buckled under the stress, tearing the ship in half before she sank. Another surprise was the condition of the wreck itself. Scientists had long believed that the seafloor at such depths was a barren wasteland, and that low temperatures, lack of oxygen, and the absence of the sea life that usually preyed upon shipwrecks would have preserved the ship in near-pristine condition. But to Ballard’s surprise the wreck was teeming with life, from sea anemones and starfish to crabs and many varieties of fish. It was also far from pristine: wood-boring molluscs had totally consumed the ship’s decks and other woodwork, while a previously undiscovered species of bacterium was slowly eating away at its iron hull, festooning the ship with stalactite-like formations Ballard dubbed “rusticles.” Further expeditions also revealed that far from tearing a large gash as was previously believed, the iceberg had merely dented the hull plates, causing water to rush in through the edges.

While Ballard attempted to photograph as much of the wreck as he could, he was careful not to touch anything, stating: “Every shipwreck, generally someone died. You don’t pick up stuff. You don’t pick up belt buckles from the Arizona. You don’t go to Gettysburg with a shovel. That’s why I left everything alone at the Titanic. It’s totally disrespectful to pick up anything …We had brought the ship back to light, but, except to land Alvin on her still-solid subdeck, we’d barely touched it, unless by accident. I had reason to hope that others would follow our lead.”

But it was not to be. Since Ballard’s first dive in 1986, dozens of expeditions have visited the wreck of the Titanic. While some, like the three dives made by filmmaker James Cameron in 1995, 2001, and 2005, sought only to film and explore the wreck, others were more exploitative in nature, raising thousands of artefacts from the seafloor including a 20-ton section of the hull complete with portholes, currently on display in the Luxor Las Vegas hotel and casino. Such activities have sparked fierce debate between “conservationists” like Ballard and “preservationists,” who argue that as much of the wreck as possible should be raised and preserved before it disappears entirely. Indeed, given the wreck’s current rate of decay – significantly accelerated by damage inflicted by salvage operations – it is estimated that by 2040 nothing will remain of Titanic but a large rust stain on the seafloor. But in a way, the Titanic has been preserved, in the countless photographs and hours of high-definition footage which have been taken of the wreck  – records that will persist long after the physical wreck itself has crumbled to dust. Thus, thanks to a pair of Cold War submarines, a determined oceanographer, and some extraordinary luck, the memory of Titanic will go on.

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