The eight-year old veteran of World War II in the Pacific was gone but not forgotten, although the exact location where the hulk slumbered in the darkness of the sea was not precisely marked. In those early years of the Cold War, marking the resting place of a ship that bore the scars of two atomic weapon tests and then served as the genesis of the Naval Radiological Defense Laboratory might well have served as a beacon for future deep-sea espionage by the Soviet Union.
We have just returned from the wreck, as the lead scientist and expedition leader of the first scientific mission to dive to the Independence and document the sunken carrier through extensive video, high-resolution photography, and digital mapping. Our mission, on board the exploration vessel Nautilus of the Ocean Exploration Trust and headed by Dr. Robert D. Ballard, was funded by the Office of Naval Research and the Office of Ocean Exploration and Research (OER) of the National Oceanic and Atmospheric Administration (NOAA).
One of the hallmarks of the Nautilus—as well as its partner in deep-sea exploration, NOAA’s Okeanos Explorer—is satellite- and Internet-based “telepresence,” which not only allows fellow scientists ashore to participate in multidisciplinary research, but also lets the public watch in “real time.” On the Independence mission in late August, the 48-member team on board the Nautilus was joined by a global audience estimated to be in the millions. It included veterans and families of the “Mighty I,” as well as those who participated in the atomic tests at Bikini 70 years ago, where the Independence faced the brunt of two detonations of the United States’ first nuclear weapon, the Mk III “Fat Man” bomb used just one time earlier against Nagasaki on 9 August 1945.
The Independence rests in 2,713 feet of water in NOAA’s Monterey Bay National Marine Sanctuary. The dives were part of an OER-funded mission along the Pacific Coast that explored the depths from the Straits of Juan de Fuca to the Channel Islands of California, primarily but not exclusively in the waters of NOAA’s five national marine sanctuaries on the coast. On this, the last diving leg of the several-months-long mission, we were joined by co-lead Jan Roletto, the research coordinator for Greater Farallones National Marine Sanctuary; scientists and digital mapping experts Drs. Chris Roman and Ian Vaughan; Dr. Ballard; and other scientists and distinguished guests to explore and map deep-sea coral, undocumented slopes of the continental shelf, marine life, and three shipwrecks, culminating in the first views ever of the Independence since the ship sank.
The first dive was a 24-hour marathon that demonstrated the skill of the Nautilus crew, the science team’s navigators, and the pilots of the remotely operated vehicles (ROVs) Argus and Hercules. We were guided by a detailed sonar image of the wreck, captured in March 2015 on a NOAA expedition with the Boeing Company and the Coda Octopus, to more precisely delineate the wreck working from the NOAA research vessel Fulmar. The wreck had been relocated during a 1990 U.S. Geological Survey mapping expedition, and again by the Okeanos Explorer, but the hull-mounted sonar systems only confirmed that something that was basically the right size and general shape lay down there. The 2015 mission confirmed a seemingly intact carrier but gave no sense as to the condition of the wreck, what lay near, on, or inside of it, or of critical importance to the 2016 dives, what might pose a hazard to the Hercules as it ventured across, and ultimately down into the hangar deck.
That meant patient, cautious work to assess the road ahead, as well as what lay in the water column on all sides that could potentially snag or collapse onto the Hercules if we ventured beneath overhanging structure. It takes more than a half hour for the Hercules to slowly drop to the seabed and then, sonar sweeping ahead into the darkness, to approach the wreck. We were rewarded, at last, as the stern of the Independence came into view out of the gloom. Buried deep in the mud to its original waterline, the stern still bears the marks of the Able Test detonation of 1 July 1946. The port quarter is defined by heavily dented hull plating, a partially crushed starboard torpedo blister, aft compartments blown open, and the upturned edge of the flight deck.
As the ROV moved along the hull, and then up and over the flight deck, damage described in once-classified reports was still clearly discernible, with little change after seven decades. We saw catwalks and gun tubs that were twisted, a hangar blown open by peak pressures that shot the elevators out of their shafts, and a flight deck displaced and thrust up along a center line so that it now resembles a peaked roof. Hatches were blown open, deadlights shattered, and at the island, the atomic wind had stripped it of its mast and antennas.
We learned that while the carrier sank by the stern, she quickly righted and plunged into the seabed at a fair rate of speed by the bow, plowing into the mud with enough force to deform it. The bow is buried up to the level of the hawse pipes. They are empty, but above them the anchor chain, shorn of anchors, dangles down either beam, connecting to the tow bridle that was slipped by the escorting tugs on that long-ago January morning. The bow hit at an angle that caused it to flex around frame 10, breaking the hull, which remains attached, perhaps held together only by the mud that enshrouds it.
The wreck is covered with marine life, primarily a healthy colony of deep-sea sponges that have made portions of the carrier an undersea garden, which is fitting given that it lies within a national marine sanctuary. Paint still adheres to the hull, including place marks made for the atomic tests that delineate frame numbers. A careful survey of the fantail rewarded us with the unexpected view of the carrier’s name, with paint still adhering to the raised steel letters. Not all wrecks yield their identity to explorers, but 65 years on, the Independence proudly retains her name.
We also documented equipment left on board for the tests—dual 40-mm antiaircraft guns and Mark 51 gun directors still in their tubs along the edge of the flight deck, and two 20-mm guns that, with their tubs, had torn free and fallen to the seabed. The aircraft crane’s tower still stands, but we did not find its working end until our second dive, when a drop into the aft elevator found it stowed there against the port bulkhead at the bottom of the shaft. We also observed two welded steel towers used to mount pressure gauges for the atomic tests. Known as “Christmas trees” at Bikini, they are iconic artifacts. One remains in place in a 40-mm tub at the bow, the other, once on the port edge of the flight deck at frame 80, now lies tumbled onto its side on the seabed.
The Coda Octopus image of 2015 had the suggestive shape of what we thought might be an aircraft in the forward elevator shaft. We were rewarded when we dropped into it to find the battered remains of an F6F-5N Hellcat fighter, which we believe was blown into the shaft when the Independence listed 40 degrees to starboard when hit by the 23-kiloton Able blast. We later found the remains of a second aircraft on the hangar deck at frame 80 in the form of a sheared wing of an SBF-4E (a variant of the famed SB2C) Helldiver. A crumpled mass of aluminum inside the hangar at frame 75 starboard may be part of this, or another target aircraft left inside the ship.
A key question for the survey was not only documentation but also assessing one aspect of the Independence’s atomic legacy. We know from detailed studies that radiation readings, while initially high after the tests, had declined significantly, and that the ship posed no radiological risk when scuttled in 1951. But once-classified documents noted that the ship also had been used as a receptacle for what was described as “low-level” waste. This included marine growth taken from the hull, laboratory and decontamination gear, and machinery and parts taken not only from the Independence but also from other target vessels from the atomic tests. Once classified reports noted that most of this, originally stowed at the hangar level, had been moved below to the engineering compartments where a turbine and boilers had been removed.
For years, popular belief—and rumor—circulated that the Independence sits in the sanctuary as a radiological risk both from her hull and from what has been thought to be hundreds of 50-gallon drums of waste strewn across the seabed and inside the hangar. Working with Dr. Kai Vetter of the University of California, Berkeley, and his students, the mission scanned and recovered some of the sponges growing on the wreck. The radiation readings proved to be no higher than ambient levels of sea water. Our survey saw no barrels or drums on the seabed, and we found only five inside the forward hangar. As per regulations of the time, they were capped with concrete. Time has corroded them, and the one we found exposed to the sea, on its side, revealed disposed surgical gloves. Dr. Vetter believes, as do others, that the Independence poses no risk. Instead, it is a near-frozen moment in time, speaking not only to its proud wartime history, but also as an evocative artifact of the dawn of the atomic age.
We ended the dives on each occasion with a somber but proud note. Lining up above the starboard catapult, we shared the story of the Mighty I’s crew and of the planes that launched off that deck as we flew slowly along the line, and Hercules passed over the edge and into the darkness as the Independence faded from view. Not all of them made it back to the carrier. It is a story repeated on other carriers, as well as by other ships and other crews, who sailed or flew into harm’s way. For all of us, the Independence in the darkness also speaks powerfully to service and sacrifice that will never be forgotten.