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By John Moyer
Header image of the sinking of the Andrea Doria July 27, 1956, and other photographs courtesy of John Moyer unless noted.
This year marks the 65th anniversary of the sinking of the Italian liner SS Andrea Doria. During the four years the ship sailed between Italy and New York, she was known as a “Floating Art Gallery.” The aftermath of the collision with the Swedish vessel, Stockholm, 80 km/50 miles south of Nantucket Island off the coast of Massachusetts, was described as the greatest sea rescue in history.
Peter Gimbel was the first diver on the wreck on July 27, 1956—the day after it sank—and he returned the following year to photograph it again for Life Magazine. Capt. Dan Turner took a team of divers to the wreck aboard his ship the Top Cat in 1964. Turner blew a hole in the Promenade Deck and recovered the life-sized bronze statue of Admiral Andrea Doria from the First Class Lounge. Unable to free the statue’s base from the deck, they cut it off at the ankles with hacksaws. Four years later, Italian film producer Bruno Vailati led an expedition to survey the wreck and determine if it could be refloated. The Fate of the Andrea Doria(English title) was comprised of footage taken throughout the expedition team’s 21 dives, and the journey inspired Stefano Carletti’s classic book, Andrea Doria-74.
Gimbel returned to the Doria in 1975 to test his theories on exactly what caused the ship to sink; this research inspired his film, The Mystery of the Andrea Doria. He discovered that the Doria had sustained massive damage to it’s hull when the Stockholm hit. During his next expedition in 1981, Gimbel and his team salvaged the ship’s safe, which he opened later that year on live TV. Various other teams also investigated (or attempted to investigate) the wreck during this time period. Some just explored the sunken vessel, some returned home empty-handed, and some didn’t even make it to the wreck site.
I remember hearing about the Andrea Doria for the first time in 1975 at a shipwreck artifact show in Brielle, New Jersey; the Eastern Divers Association orchestrated the event. I met some divers there who told me about a wreck they described as the “Mt. Everest of Diving.” She was a massive 213 m/699 ft-long passenger liner lying on her starboard side, 74 m/241 ft in the cold, dark North Atlantic. That area of the ocean is known for frequent storms, rough seas, and strong currents. The divers said they often had to pull themselves hand-over-hand down the anchor line, fighting to reach the bottom. Visibility averages about 8 m/26 ft, so they had to be careful not to get hung up in the commercial fishing nets that had snagged the exterior of the wreck. Because she is on her side, it’s easy to become disoriented when penetrating the wreck. The interior is a confusing maze of ceilings that are now walls, walls that are now floors, and stairwells that run sideways. It is filled with silt; the water may be clear when you swim in, but picking up an artifact decimates the visibility, so divers often have to feel their way out. Steel cables and wires hang down, and divers can easily become entangled. When I left that show, I knew I wanted to see the Andrea Doria for myself.
My First Doria Dives
In 1982, I dived the wreck for the first time with a small group of divers on a chartered boat. We anchored at the forward end of the Promenade Deck, and I made three dives exploring the area. My first finds were two silver jewelry boxes and a brass-framed window. The next year, we began diving into the ship’s first class dining room where we found piles of china dishes and glassware. In 1985, a dive team and I spent a week on the wreck and recovered the 68 kg/150 lb brass bell from the ship’s aft steering station.
After that 1985 trip, I began my serious research into the ship and collected everything I could find related to the Andrea Doria. I traveled to Italy to meet with the engineers at Ansaldo Shipyard—who had designed the ship—and the Italia Line officers who were onboard the night of the collision. I also corresponded with Bruno Vailati to get his insight into diving on the wreck. Between 1985 and 1991, we made many trips out to the site, exploring new areas of the wreck and recovering any artifacts we found.
In 1992, based on information I had received from Italy, Billy Deans and I began searching the bow of the wreck for the ship’s main bell. We entered through a hatch, swam along a corridor, then up a hallway to the room where I was told it was stored. When I pried opened the door, I found the room was filled with about 1 m/3 ft of silt and debris. Later that year, I took a team of 15 divers and crew aboard the R/V Wahoo and spent a week cleaning out the room with an airlift. Unfortunately, we did not find the bell.
During the winter of 1992-1993, Rinaldo Negri, who had helped design the Andrea Doria, sent me a book with a photo of the ship’s Wintergarden Lounge; the photo captured the lounge’s large wall panels inlaid with ceramic sculptures created by Italian artist Guido Gambone. I was able to match that photo with the ship’s plans and determine exactly where the works of art were on the ship. Billy Deans and I dove into the Wintergarden and found that two panels had fallen from their mountings and were lying deep inside the wreck. Later that summer, I returned on the R/V Wahoo, this time with a team of 20 divers and crew, to recover the panels. Over a period of four days, working in near zero visibility at a depth of 61 m/199 ft, the team rigged each 454 kg/1,000 lb panel with inflatable lift bags and floated them to the surface.
Prior to the expedition, my attorney filed legal papers in the US District Court in Camden, New Jersey. Judge Joseph Rodriquez granted an Admiralty Arrest, asserting the court’s jurisdiction over the Doria, and appointed me custodian of the wreck. I was required to attach the signed arrest papers (inside a sealed container) to the wreck. Later that year, we again appeared before Judge Rodriquez. We argued that, although insured by an Italian consortium, the underwriters had made no attempt at salvage in nearly 40 years; therefore, they had abandoned the wreck. The court agreed and named me Salvor-in-Possession. This gave me exclusive salvage rights, clear title, and ownership of anything we recovered. I did not want to shut the wreck down from recreational divers and have allowed them to continue to dive it, to photograph, and to recover small artifacts. In his ruling, the Judge stated: “Moyer’s independent research and archeological documentation of salvage efforts indicate a respect for the Andrea Doria as something more than just a commercial salvage project.”
Displaying The Doria
From the very beginning, my intention was to collect certain artifacts from the wreck and as many items related to the ship that I could find. I wanted to create an Andrea Doria exhibit to tell the story of what some call the most beautiful ship to ever sail. I have put on dozens of temporary exhibits and displays over the years and hope someday to have a large permanent exhibit. The general public has always been very interested and pleased to see what we have recovered. I am also working closely with Andrea Doria survivor Pierette Simpson. She is the author of Alive On The Andrea Doria and produced the award winning film Andrea Doria: Are the Passengers Saved?
We have held many events, participated in film screenings together, and have ridden in the New York City Columbus Day Parade (along with other survivors and Ted Hess, lead diver of Gimbel’s 1981 expedition). At the end of the parade, there was a ceremony where Pierette rang the Andrea Doria bell in memory of the souls who lost their lives in the sinking. We are currently working with The Noble Maritime Collection in Staten Island, New York on an exhibition which will open late spring 2022.
The inevitable decay of sunken ships is slow and most often unobserved. The sinking of the Andrea Doria produced a wreck of very unusual characteristics. Due to newsreel camera planes circling overhead, it became world famous, and its final resting place is accessible to divers. When Peter Gimbel first visited the wreck in 1956, he saw no obvious damage to the ship. Since then, divers have been reporting major decay events on the wreck. The wheelhouse was still intact when the Italian dive team filmed it in 1968, but it was gone by 1973. The funnel, mast, and top three decks of the superstructure had fallen off by the time I first dove it in 1982. We used the port side bridge wing as a landmark until it fell off sometime in the early 1990s. The Wintergarden was completely intact when we recovered the Gambone sculptures in 1993, but it totally collapsed only two years later.
Later in the 1990s, we noted cracks in the hull and the Boat Deck, Upper Deck, and Foyer Deck had started to slide downward to the sea floor. A recent multibeam sonar scan by the University of New Hampshire showed that the cracks have expanded and that the hull has entered its final stage of the flattening process.
Someday the Andrea Doria will be an unrecognizable pile of debris on the bottom of the sea. Fortunately, we have been able to rescue many historically important artifacts and unique works of art before they were lost forever.
InDepth: Stefano Carletti: The Man Who Immortalized The Wreck of the Andrea Doria By Andrea Murdock Alpini
Alert Diver: Remembering the Andrea Doria by Michael menduno
Diver: Doria Tipped The Scales by Michael Menduno
John Moyer’s first dives were in 1970, and he began diving on shipwrecks in 1975. He has made thousands of dives on wrecks in the US, Canada, Great Britain, Mexico, and the Caribbean. He has dived on the liner RMS Empress Of Ireland, Ironclad Monitor, Light Cruiser USS Wilkes-Barre, and was one of the first Americans to dive on the WW1 German fleet in Scapa Flow, Scotland.
He has a degree in Biology from Stockton University, a USCG 100 Ton Master License, and worked as an Instructor at the Dive Shop of New Jersey and Key West Divers. Moyer is a member of the Atlantic Wreck Divers Dive Club and is the recipient of the prestigious Pioneer of Northeast Diving Award. He has appeared on the History Channel, A&E Network, and Dateline NBC. He is co-author of “The Decay of the Andrea Doria,” published by the Society of Naval Architects and Marine Engineers, and he appears in the docufilm Andrea Doria: Are the Passengers Saved?
High Pressure Problems on Über-Deep Dives: Dealing with HPNS
If you’re diving beyond 150 m/490 ft you’re likely to experience the effects of High Pressure Nervous Syndrome (HPNS). Here InDepth’s science geek Reilly Fogarty discusses the physiology of deep helium diving, explains the mechanisms believed to be behind HPNS, and explores its real world implications with über-deep cave explorers Dr. Richard “Harry” Harris and Nuno Gomes. Included is a list of sub-250 m tech diving fatalities.
By Reilly Fogarty
Header image: Original Photo by Sean Romanowski, effects by the team at GUE HQ
There aren’t many technical divers exploring deeper than 153 m/500 ft on a regular basis—the logistical and physiological demands alone make sure of that. The small group of divers who do reach those depths without saturation chambers or other professional accoutrements face a daunting host of new concerns. At these depths, decompression models aren’t as well validated, and dives require precise gas planning and acknowledgement of extreme environmental exposures.
As if decompression illness (DCI) and oxygen toxicity risks weren’t enough, divers must prepare to deal with the possibility that they may get to depth and experience vertigo, confusion, seizures, and a varied list of other neurological maladies—sometimes without warning. These symptoms are the result of high-pressure nervous syndrome (sometimes called high-pressure neurological syndrome) or HPNS. Symptoms of HPNS are highly variable but primarily affect those who descend rapidly to 153 m/500 ft or deeper. HPNS may have played a role in the death of legendary cave explorer Sheck Exley, and it may have caused numerous close-calls in deep cave and wreck explorations. But, the extreme depth required to experience onset has relegated research and education on HPNS to a niche corner of the diving community—one with significant interplay with the commercial saturation diving world and the most extreme sport communities.
The Physiology of Deep Helium Diving
In 1961, G.L. Zal’tsman, who headed the Laboratory of Hyperbaric Physiology, St. Petersburg, Russia, first identified what would eventually become known as high-pressure nervous syndrome. The political climate of the period limited access to his work in the west, so credit for the discovery is often shared with Peter Bennett, D.Sc, who published a paper on the subject in 1965. While politics and international tensions separated them, both researchers described what they called “helium tremors” that occurred during experiments with military subjects. Using gases with the high helium content required to manage narcosis at depth, participants in these studies were observed experiencing uncontrollable muscle tremors upon compression in a chamber.
At the time, it was unknown if this was a function of the helium in their breathing gas or an effect of depth. The term “high-pressure nervous syndrome” originated just a few years after Zal’tsman’s study, when R.W. Brauer identified changes in the conscious states and electroencephalography data from subjects in a chamber dive to nearly 368 m/1,200 ft. In the decades since, several studies further illuminated what we now know as HPNS, primarily as a result of research into deep sea exploration from the 1970s to early 1990s. As it stands now, HPNS is primarily identified by a decreased mental status, dizziness, visual disturbances, nausea, drowsiness, muscle tremors, and seizures in divers rapidly reaching depths of 153 m/500 ft or more, or exploring the extremes of depth closer to 306 m/1,000 ft at any rate of compression while breathing a high helium content gas.
The prevailing theory is that a combination of speed of compression during descent, and the absolute pressure at depth, cause these symptoms. Symptoms are rare during dives above 153 m/500 ft, but dives that exceed that depth, or that reach depth quickly, increase the likelihood of symptom evolution. Symptoms do not appear to correlate to each other, and individual susceptibility is highly variable, which makes predicting onset difficult. Some researchers also theorize that there are two separate conditions caused individually by compression (the symptoms of which diminish at depth) and total pressure (the symptoms of which persist throughout the bottom portion of a dive). This two-part explanation for HPNS symptoms provides some interesting avenues for future research and could help solidify some of the theorized mechanisms underlying the condition, but it has yet to be expanded upon in a significant way.
The mechanism behind HPNS has yet to be proven, but most researchers choose to work upon the basis of a few reasonable theories. The first relies on the compression of the cell membranes in the central nervous system. In this model, the rapid compression of the lipid components of these membranes may alter the function of the inter-lipid structures that facilitate signal transmission within the central nervous system. This change in structure could facilitate hyperexcitability of some nervous system pathways and cause the types of tremors and seizures associated with serious HPNS cases. This membrane compression could also alter the signaling pathways required for motor function and cognition, resulting in confusion and assorted neurological symptoms that sometimes occur in divers with HPNS.
Another model focuses on the role of neurotransmitters themselves, rather than their signaling receptors. The various iterations of this model examine the effects of pressure and varying helium/oxygen exposures on the production or reception of these transmitters. In some ways, this method resembles our understanding of oxygen toxicity mechanisms, which could lead to some interesting interplay between future research projects and the balancing of oxygen and helium exposures at extreme depth. Some of the more promising studies in this area show evidence of NMDA receptor antagonists reducing convulsions in animal models, and describe the effectiveness of increased dopamine release in preventing increased motor activity under extreme pressure in rat models.
A third model focuses on the effect of helium on HPNS risk. This model functions on a yet-unidentified mechanism, but explores the potential distortion of lipid membranes by helium at depth. The data from these studies suggests that high pressure helium—not high hydrostatic pressure—may alter the tertiary structure of protein-lipid interactions and change signaling pathways within the nervous system. Numerous other avenues for research exist in this niche, including projects working on a great number of neurotransmitter related conditions and pre-treatment protocols for HPNS, oxygen toxicity, and possibly related normobaric diseases. Any of these models could prove accurate, but the interplay between the many neurotransmitters makes it most likely that a combination of these models will best illustrate what occurs in-situ.
Experienced firsthand, HPNS is far less academic, but equal parts confounding and terrifying. The variable onset and sometimes ambiguous symptom presentation make it difficult to discern from other conditions, and mild symptoms can be easily written off. By the same token, however, a serious bout of tremors or confusion as a result of a rapid descent to deep water can leave a diver terrified and unable to act. Dr. Richard “Harry” Harris, SC OAM, is a physician and technical diver with years of exploration in deep caves and shipwrecks. His experiences with HPNS mirror that of many. Most often, he’s observed symptoms like trembling hands or loss of coordination that could be attributed to either HPNS or the adrenaline rush of a fast hot-drop from a boat in heavy seas.
On one recent dive to 150 m/490 ft, Harris described becoming temporarily incapacitated on the bottom due to minor tremors, finding himself unable to clip his strobe to the shot line. The symptoms resemble common descriptions of mild HPNS symptoms, but the relatively shallow (in terms of HPNS, at least) depth still gives him pause when he tries to discern the specific cause of the symptoms. Dives past 200 m/656 ft have provided similar conundrums, but Harris has experienced tremors at extreme depths with enough regularity to notice that he is somewhat more susceptible than his regular dive buddy Craig Challen. “This [variation in symptom onset and presentation] has really made me question again the role of the mental state, approach, and perhaps even intentional mindfulness on these symptoms,” explains Harris.
By focusing on gas choices that strike a balance between gas density and the high concentrations of helium that can cause HPNS symptoms, and by descending relatively slowly, Harris has managed to alleviate symptoms on much deeper dives. A recent 245 m/799 ft dive with an intentionally slowed descent gave him none of the same complaints as his rapid descents to shallower water and felt “like a [much shallower] 150 m/490 ft dive.”
It’s worth noting at this point that Harris and Challen are extraordinarily capable and experienced divers, and HPNS is a condition that shouldn’t be taken lightly. Their approach—a combination of conservatism and safety—is likely key to their management of HPNS on extremely deep dives. Other divers, some equally experienced, have not been as fortunate in the past.
Sheck Exley reported a particularly bad case during a dive to 210 m/689 ft, with vision blurred to the extent that he was “looking through small circles with black dots, and started convulsing.” Despite these symptoms, he continued his dive, and proceeded to a maximum depth of 263 m/863 ft. It’s thought that Exley’s eventual death during an attempt to descend past 305 m/1,000 feet in the Mexican Zacatón cave system could have been caused in part by HPNS symptoms exacerbated by narcosis.
Nuno Gomes, a technical diver who holds several Guinness World Records for depth in open water and in caves, has also become intimately acquainted with HPNS, experiencing the following during a world record dive:
“As I descended past 250 m/816 ft, the HPNS set in. At first, relatively mild, then fairly strong. And later on, the symptoms became so extreme that my whole body shook uncontrollably. One other problem was lack of coordination of movement. I felt severely narcosed on my bottom trimix of 3.15/85. It had only a calculated END of 40 m/131 ft. From my experience, a more realistic narcosis level was 78 m/256 ft as calculated using the Total Narcotic Depth (TND). When I reached the tag marked 315 m/1,033 ft at an actual depth of between 322 m/1,056 ft and 323 m/1061 ft, I realized that this was as far as I was able to go. I was not sure that I would be able to return if I went any deeper. At that stage, I was not sure that I would be able to swim up from that depth.”
Gomes’s regular attempts to reach extreme depth made him uniquely prepared to identify symptoms of HPNS as they appeared, but even with his breadth of experience, the effects of the condition could have become lethal if allowed to continue.
Statistically, there just aren’t enough documented cases of HPNS to make for a meaningful analysis, but these incidents can provide a basis for education. The symptom severity and onset variability is enormous, but there are some trends that can be pulled from the stories of Harris, Exley, and Gomes. How to integrate those in your dive plan without meaningful data to back them up, however, falls to personal choice.
Planning for the Future
There are more than a few good reasons not to end this piece with a “how-to” on diving past 153 m/500 ft. With regard to HPNS specifically, the reality is that we just don’t know enough about the mechanisms that cause the symptoms divers experience. What we have is an understanding that high helium content and rapid descents likely contribute to HPNS risk, some people are more susceptible than others, and the symptom presentation is not uniform or predictable. Beyond these fundamental constants, we must piece together what we know from the limited research we do have and the experiences of others.
The data on compression speed appears to be pretty clear: HPNS symptoms may not be entirely preventable, but the risks can be somewhat ameliorated by slowing our descent speeds. There also appears to be an opposing effect between helium and nitrogen content in our breathing gas. This is likely due to changes in the structures of the membranes surrounding our central nervous system caused by helium and other inert gases, requiring divers to balance potential narcotic effects and HPNS risk in gas planning.
Using nitrogen as a protective gas seems counterintuitive, but in some extremely deep dives, adding just 5% nitrogen to a heliox mixture appeared to dramatically reduce HPNS symptoms in divers. However, the extent of practical efficacy remains to be seen. Promising studies researched using hydrogen to minimize HPNS risk, but this avenue of research is prohibitively expensive and logistically challenging due to the inherent fire risk.
The onset of HPNS symptoms also appears to be relatively gradual, although it’s important to recognize that not all data supports this and rapid onset can occur. With slow descent rates and intelligent gas choices, it seems unlikely that divers would experience HPNS severe enough to incapacitate them before they had a chance to turn their dive, but that is not to say that it cannot happen or should be ignored as a real concern. Symptoms of HPNS still haven’t been found to correlate with each other, and not only can new symptoms arise quickly, but also the nature of the ailments means that a diver may not be able to identify symptoms until it is too late to react.
The past decade has failed to provide much in significant data on HPNS as it pertains to recreational divers, certainly almost nothing in comparison to the deep-diving heyday that brought about the COMEX tables and Atlantis projects. Going forward, it seems likely that HPNS will become a greater concern. Technical divers will continue to explore the limits of depth with the widespread adoption of rebreathers, persisting in their search for deeper caves and unexplored wrecks. Hopefully, this ongoing—perhaps even increasing—activity will spur more research into HPNS and the potential interplay between the mechanisms of narcosis and oxygen toxicity. Until then, we’ll have to continue to glean what we can from the data we have and the experiences of the more ambitious among us.
- Naquet, R., Lemaire, C., J.-C. Rostain, & Angel, A. (1984). High Pressure Nervous Syndrome: Psychometric and Clinico- Electrophysiological Correlations [and Discussion]. Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences, 304(1118), 95-102. Retrieved May 21, 2021, from http://www.jstor.org/stable/2396156
- Talpalar, Adolfo. (2007). High pressure neurological syndrome. Revista de neurologia. 45. 631-636.
- Understanding Oxygen Toxicity: Part 1 – Looking Back
- Pearce PC, Halsey MJ, MacLean CJ, Ward EM, Webster MT, Luff NP, Pearson J, Charlett A, Meldrum BS. The effects of the competitive NMDA receptor antagonist CPP on the high pressure neurological syndrome in a primate model. Neuropharmacology. 1991 Jul;30(7):787-96. doi: 10.1016/0028-3908(91)90187-g. PMID: 1833661.
- Kriem B, Abraini JH, Rostain JC. Role of 5-HT1b receptor in the pressure-induced behavioral and neurochemical disorders in rats. Pharmacol Biochem Behav. 1996 Feb;53(2):257-64. doi: 10.1016/0091-3057(95)00209-x. PMID: 8808129.
- Bliznyuk, A., Grossman, Y. & Moskovitz, Y. The effect of high pressure on the NMDA receptor: molecular dynamics simulations. Sci Rep 9, 10814 (2019). https://doi.org/10.1038/s41598-019-47102-x
- High Pressure Neurological Syndrome, DIVER (2012) by Dr. David Sawatzky
InDepth: Diving Beyond 250 Meters: The Deepest Cave Dives Today Compared to the Nineties by Michael Menduno & Nuno Gomes
aquaCORPS:Accident Analysis Report from aquaCORPS #9 Wreckers (JAN95):What happened to Sheck Exley? by Bill Hamilton, Ann Kristovich And Jim Bowden
InDepth: Thoughts on Diving To Great Depths by Jim Bowden
InDepth: Playing with Fire: Hydrogen as a Diving Gas By Reilly Fogarty
Reilly Fogarty is an expert in diving safety, hyperbaric research, and risk management. Recent work has included research at the Duke Center for Hyperbaric Medicine and Environmental Physiology, risk management program creation at Divers Alert Network, and emergency simulation training for Harvard Medical School. A USCG licensed captain, he can most often be found running technical charters and teaching rebreather diving in Gloucester, Massachusetts.
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