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By Michael Menduno
Header photo by Barry McGill
The advent of mixed gas usage by sport divers—the so-called “Technical Diving Revolution”—in the early to mid-1990s greatly expanded our community’s underwater envelope, while arguably improving diving safety.
In order to appreciate how far, err deep, we have collectively come, I thought it would be illustrative to contrast the deepest tech shipwreck dives today from those in the 1990s when technical diving was just getting started.
Back in the early to mid-90s, technical diving pioneer Capt. Billy Deans, owner of Key West Diver observed that mix technology enabled us to “double our underwater playground.” Deans was contrasting the then existing recreational diving limits i.e. No stop dives to 130 ft/40 m to the new technical diving envelope that was made possible with the use of helium-based bottom gas and accelerated decompression using nitrox and oxygen. Note that during this period, the words Deep (beyond 40 m) and Decompression i.e. “The D-words,” were considered four-letter words by many in the recreational diving establishment.
At the time, we considered open water decompression dives with 15-25 min of bottom time to depths of 260 ft/79 m to represent a reasonably safe envelope for mixed gas tech dives, hence Dean’s comment about doubling of our recreational playground. Because of the ability to more easily stage bailout and decompression gas in the cave environment, the envelope there was considered deeper/longer. That is not to say that tekkies weren’t diving deeper than 260 ft/79 m and staying longer, but at that time, we considered these dives as “exceptional,” requiring special methods and work.
Deep Shipwreck Dives in The 1990s
The first table (below) highlights the ten deepest tech wreck dives from 1989-1999, including the location, depth, dive profile, technology used and the technical divers who first dived the wreck in question. The majority of these dives was reported at the time in my magazine aquaCORPS Journal.
The deepest tech shipwreck dive at the time was on the Edmund Fitzgerald lying in 530 feet (162 meters) of fresh water in Lake Superior the equivalent of 514 ft/157 m of sea water. The shallowest was the RMS Lusitania near Kinsale, Ireland at 310 ft/95 msw.
Note that the depths listed in both tables should be considered as relative metrics. In most cases, the depth indicates the depth at the bottom of the wreck. In some cases, divers actually dived to the bottom. In other cases, the depth indicates the depth that divers actually reached. In other words, the depth numbers are a bit fuzzy.
There are several observations to be made. First, all of these dives but one, were conducted on open circuit scuba. At the time literally, only a handful of technical divers had rebreathers, which were either modified Carleton Mk 15.5s, Dr. Bill Stone’s handmade Cis-Lunar rebreathers, the Halcyon PVR-BASC semi-closed rebreather aka “The Fridge,” the predecessor of the RB80, or various prototypes. AP Diving’s Inspiration, the first production rebreather, wouldn’t be released until 1997. In the case of the RMS Niagara (392 ft/120 m), Tim Cashman and Dave Apperly were using rebreathers made by Apperly. Though mixed gas technology was a necessary precursor, rebreather usage would not hit its stride for another decade.
Two of the dives shown on the chart, the SMS Frankfurt (420 f/129 m) dived in 1994, and the Ostfriesland (380 f/117 m) dived in 1990, were conducted by wreck diving pioneers Ken Clayton and Gary Gentile on heliox. Clayton also dived an experimental Neox mix (02 and Ne) for their last dive on Ostfriesland to 340 f/104 m with 20 min BT.
In 1989, the Clayton, Gentile and their team also conducted a deep air dive, with air decompression—can you imagine??—on the USS Washington (290 ft/89 m), which would have been #11 in the 1990s table. Ironically, though cave divers quickly embraced “special mix” technology, the majority of dedicated U.S. Northeast wreck divers were slow to adopt mix technology to replace their deep air diving though they did add oxygen and or nitrox for decompression.
In terms of divers, Terrence Tysall, now the training director for National Association of Underwater Instructors (NAUI), made the two deepest dives on the list in 1995, first on the Fitzgerald in 1995 with Mike “Zee” Zlatopolsky, and then on the Atlanta with Aussie pioneer Kevin Denlay.
Though the rumor was that Tysall and Zee had made a “sneak dive” on the Fitzgerald which was a grave site, the two were able to obtain a permit, but it did not allow them to tie into the wreck. They ended up using the drop camera umbilical as a downline, and left a plaque on the “Fitz” to commemorate the sailors that had been lost. However, they were only able to make a single dive due to the weather.
Clayton, Gentile and their teammates accounted for three of the ten deepest wrecks while Gentile was involved with four of 10, and Deans and his team accounted for two dives on the list. Note also that British tekkie Polly Tapson, one of the first female tech expedition leaders, and her team Starfish Enterprise captured the imagination of the community at the time with the preparations and their successful dives on the “Lucy” in 1994.
Three years later, British tech pioneer and inventor Kevin Gurr launched the first technical expedition on the Britannic with Dave Thompson, founder of JJ CCR, Al Wright, Global Underwater Explorers’ (GUE) Richard Lundgren, his brother, photographer Ingmar Lundgren, photographer Dan Burton, and British tekkie John Thornton. Of course, the wreck was first discovered and dived by Jacques Cousteau and his team in 1976, see footnote.
In terms of depth, the average depth of these 1990s wrecks is 389 ft/122 m average bottom time: 16.7 min, and average run time: 192 min or just more than three hours.
The Deepest Shipwreck Dives Today
The second table shows the 30 deepest technical shipwreck dives as of this year identifying the first tech teams to dive on the wrecks. Note that only the eight deepest shipwreck dives from the 1990s made it on the list. The deepest tech shipwreck dive, was on the Milano lying at a depth of 774 fresh water (236 mfw) in Lake Maggiore, Italy, (the equivalent of 751 fsw/176 msw), conducted by Pim van der Horst, Mario Marconi, and Alessandro Scuotto in 2008, with the help of diving pioneer Nuno Gomes who was a consultant and witnessed the dive.
The 30th deepest wreck dive is now the SMS Ostfriesland (380 ft/116 m), which was just slightly shallower than the average depth of the Ten Deepest Shipwrecks from 1990. The deepest wreck dive in the 1990s, that being the SS Edmund Fitzgerald, aka ‘The Fitz,” laying at 529 ffw/162 mfw, is now #11 when viewed from today. That is to say that the top ten deepest shipwreck dives were all conducted after 2000.
Note also there is one high altitude shipwreck dive on the list being the SS Tahoe at 471 feet of fresh water/144 m, the equivalent of 457 ft/140 m of seawater, which lies in Lake Tahoe at an altitude of 6224 ft/1897m. The altitude makes the SS Tahoe a no-man’s land in terms of decompression knowledge; there is almost no data to validate procedures for aggressive dives at that altitude. Only Sheck Exley and Nuno Gomes’ series of sub-500ffw/153mfw open-circuit cave dives in 1992-1996 at Boesmansgat sinkhole that lies at an altitude of 5000 ft/1500m in South Africa were possibly more extreme.
Also interesting, 9 of the 13 wreck dives in the deepest 10 today (there were multiple shipwrecks at the same depth) were conducted on rebreathers vs. four on open-circuit scuba. All but one of the 10 deepest shipwreck dives in the 90s were conducted on open circuit. All the 30 deepest dives but two, were made using trimix as a back gas or diluent, the exception was the Frankfurt and Ostfriesland first dived by Clayton and Gentile and team as noted above.
Closed-circuit technology is largely responsible for the deeper depths and longer dives we see today. The average depth of the ten deepest shipwreck dives listed in chart two is 576 ft/176m, or 178 ft/75 m deeper than the ten deepest shipwreck dives from the 1990s. Average bottom time for the deepest 10 today was 15 minutes compared to 16.7 min for the 1990s wrecks, however average run time was 316 minutes or more than five hours, compared to a little over three hours in the 1990s.
The amazingly prolific Italian diver Massimo Domenico Bondone and his team accounted for six of the dives in the 20 of the 30 deepest shipwrecks! Wow! He is followed by Irish tekkie and photographer Barry McGill, his colleague Stewie Andrews, and their various teams who were responsible for four of the deepest dives shown on the table. Aussie tekkies Dave Bardi, Craig Challen, Richard “Harry” Harris and their colleagues from the “Wet Mules,” who were prominent in the Thai cave rescue earlier this year, were responsible for three of the dives as were Ken Clayton and Gary Gentile (from the 1990s). Tysall
Was responsible for two dives on the list, the Fitzgerald and the Atlanta.
Have we bottomed out our depth capability as self-contained divers? If history is any judge likely not. My long-held belief is that self-contained atmospheric diving systems aka Exosuits or hard suits, such as those pioneered by commercial pioneer Phil Nuytten, founder and CEO of Nuytco Research, represent the next wave of technology that promises to extend our envelope even further. However, given the slow pace at which diving technology evolves (it’s a matter of economics), it may be a while before divers will have access to $10,000 swimmable Exosuit.
Even so, it will be interesting to see what the list of the 10 deepest tech shipwrecks dives will look like in 2029.
Editor’s Note: This post evolved based on input from our readers. Here were the two earlier versions:
A printed version of this article was published in the “Journal of Diving History, Third Quarter 2019, Vol 27 Number 100.
Table 1: 1990s
Deepest 10 (1989-1999): Average depth: 398 fsw/122 msw, Avg Bottom Time: 16.7 min Average Run Time: 192 min
*Note that Tysall & Zee’s dive on the Fitz was not a “sneak” dive. The two obtained permits to dive the wreck but they didn’t allow the divers to tie in.
** Denlay & Tysall’s first dive in 1995 was to 361 fsw/110msw on the shallow stern of the Atlanta. They returned in 1997/98 where they made their deepest dive to the bow.
** Jacque Cousteau, Albert Falco (team leader), Raymond Coll (camera), Ivan Giacoletto (lights) and Robert Pollio (photo), were the first to dive the Britannic in 1976. Their first recon dive was on air!! Subsequent dives with BT: 15 min were made with Trimix 14/54. The team deco’d in a bell. GUE launched its own expedition in 1999 which included the Lundgren brothers.
Table 2: 30th Deepest
Deepest 10 (1990-2018): Average depth: 576 fsw/1176 msw, Avg. Bottom Time: 15min, Avg. Run Time: 374 min
*The Jolanda sits vertically from 70-150 msw. According to M. Ellyat, Gregory ‘Banan’ Dominik found and dived the deep bit of the Yolanda in Sharm 3 years before Mark Andrews and Leigh Cunningham.
** According to M. Ellyat When he found the Victoria in 2004 it was almost intact in 156m. Subsequent dynamite fishing has blown the inner decking down to the seabed making it appear 144m.
***Rizia Ortolani set the then Deep Wreck Female record on this dive.
**** Scuttled in Operation Daylight, Operation Deadlight Type VII.
*****Denlay & Tysall’s first dive in 1995 was to 361 fsw/110msw on the shallow stern of the Atlanta. They returned in 1997/98 where they made their deepest dive to the bow.
****** The wreck had been dived previously in September 2000 by Richie Stevenson, Chris Hutchison and Dave Greig but only as a bounce w/ 2 min bottom time. Subsequent dives with BT: 15 min were made with Trimix 14/54. The team deco’d in a bell. Greek commercial diver Kostas Thoctarides followed Cousteau in 1995 making a solo 20-min dive, and returned in 2001 with a submersible.
********Clayton dived Neox mix (O2 and Ne) for their last dive on Ostfriesland to 340 f/104 m with 20 min BT.
Michael Menduno is InDepth’s executive editor and, an award-winning reporter and technologist who has written about diving and diving technology for 30 years. He coined the term “technical diving.” His magazine “aquaCORPS: The Journal for Technical Diving”(1990-1996), helped usher tech diving into mainstream sports diving. He also produced the first Tek, EUROTek, and ASIATek conferences, and organized Rebreather Forums 1.0 and 2.0. Michael received the OZTEKMedia Excellence Award in 2011, the EUROTek Lifetime Achievement Award in 2012 and the TEKDive USA Media Award in 2018.
They Discovered an 11,000-year-old Submerged Ochre Mine
The exploration crew at CINDAQ, headquartered at Zero Gravity Dive Center in Puerto Aventuras made international news this year with their discovery of an ancient submerged ochre mine. Fortunately, they were happy to share the secrets of its discovery and how they documented their find with British cave and 3D photogrammetry instructor John Kendall. Oculus Rifts anyone?
By John Kendall
Header image courtesy of CINDAQ
In 2017, underwater cave explorers Fred Devos, Christophe Le Maillot, and Sam Meacham found evidence of ancient mining activity while exploring and mapping new tunnels of an underwater cave near Akumal, Quintana Roo, Mexico. Historians know that ancient residents actively mined pigment and other minerals from the caves of the Yucatan Peninsula, but the ancient mines the CINDAQ team discovered are now submerged, indicating that such mineral exploitation occurred thousands of years ago.
At the end of the last Ice Age, intrepid miners ventured deep into these tunnels with torches in hand. The navigational markers, mining debris, fire pits, and excavation pits they left behind are now entirely underwater. Over the last three years, the three explorers (along with others) have been surveying the site and making 3D photogrammetric models of the mine workings. As the mine has been submerged for around 8,000 years, it’s been untouched since then, and it’s an amazing time capsule. The project recently hit the international news when the first results were published. I was pleased to be able to chat with Chris, Fred, and Sam to find out a bit more about the project, and the challenges faced with archaeological work in a cave environment.
John Kendall: How did you happen to find the mine?
Chris Le Maillot: As always, there was a little bit of chance involved with it. The cave—Sagitario, which is a beautiful cave behind Minotauro—was initially explored by a few local cave divers. They established an upstream and part of a downstream, dropping down in the upstream to around 22 m/72 ft, and there’s the halocline sitting at that depth. It’s not always the case, but they didn’t take any survey, absolutely nothing. So I don’t think the information was there for them to continue on with the exploration. As you know, once you have that data in and have a good concept of what the cave is doing and where it’s going, it’s easier for you to poke around and find potential continuations of the cave passages.
So one of the divers asked Fred [Devos] to get involved to create a survey. That comes from the fact that Fred previously had done some mapping for these guys. Fred had a cave survey class coming up, so he took the class there, and spent the week with the survey class mapping the downstream part. Obviously, when they got to the end of the line, Fred could see that there was potential for further exploration. But you can’t really go off exploring during a class, so he went back with Sam [Meacham].
So then you went back and explored?
Fred Devos: Exploring caves is what we’ve been doing for more than 20 years, and so it’s a regular event during the mapping of a cave to find more cave to explore. You know, when mapping, we have to swim off to measure the side walls, sometimes there isn’t a wall, and then end up exploring that passage. I was in the process of making a detailed map of this cave, and found this passage, so I went back with Sam, and we immediately realized something was unusual. Things were out of place, we started seeing rocks piled on top of each other, speleothems in places they shouldn’t have been, and the further we went the more of this we saw.
“Exploring caves is what we’ve been doing for more than 20 years, and so it’s a regular event during the mapping of a cave to find more cave to explore.”
We started picking up a little bit of flow, which is always a good thing in exploration, and that led us to this restriction, where all the water was going through, and I don’t think we’d have made it through if the restriction hadn’t been manipulated before we got there. So, you know, speleothems were smashed out, and it really looked like 100 divers had gone through there before us, which really piqued our curiosity as we knew no one had been there before us. We happened to be in back mount during this dive and I managed to squeeze through there and called Sam through, and that was when we first saw irrefutable evidence of what humans had been doing in this cave—you know, pre-8,000 years ago.
“It was pretty clear to anyone what we were seeing, that people had been digging in here, smashing open the floor and pulling out huge amounts of sediment and piling stuff out of the way. It was super exciting.”
We didn’t have to wait for lab results to come back or ask an archaeologist about it. It was pretty clear to anyone what we were seeing, that people had been digging in here, smashing open the floor and pulling out huge amounts of sediment and piling stuff out of the way. It was super exciting, as it was something we’d suspected for quite a while but had never really determined for sure that was what we were seeing. But this time it was obvious, and there was no question about it.
So, how large an area does the mine occupy?
Sam Meacham: It’s about 250 m/817 ft of cave passageways that are exemplary of the mining activity, and everything we’re seeing there shows the things that people were doing in the mine.
Devos: And we haven’t finished exploring yet. There are hectares of mining area, so it’s not just one hole that’s been dug out. It’s entire passages and we’re talking about hundreds, maybe thousands of tons of material, and remember we have dates spanning maybe a 2,000-year period.
What makes La Mina so significant from a scientific point of view?
Devos: The amount of workings means that this was a massive undertaking. Not just the mining itself, but it’s clear it wasn’t just a one-person adventure. It must have been multi-generational, but beyond that it speaks very much about the organization of the people of that time. So as you can imagine, they were in a dark cave and needed fire for light. So they needed people to bring in the firewood, and others to cart out the material, and there were probably explorers at the time. You know, people that ventured further into the caves away from the exit into the smaller passages…to find this very valuable resource. And I imagine they were the ones that were being punished somehow because the risk involved was probably much greater. So, you know, if they didn’t do their work well in the mine, they probably got sent to explore.
So are there any archaeological signs on the surface around the mine?
Devos: Well there probably are, there’s certainly Maya era archaeology, and in almost every cave we see evidence of that, but we’re talking about 5,000 years ago. The mine was even further back, so anything that was once there won’t be anymore, and the only place we are likely to find anything is in the caves.
Let’s chat about the photogrammetry side. More and more people are hearing about photogrammetry, but I think the readers will be interested to hear a bit more about the challenges that you faced doing photogrammetry in a cave environment, where everything around you is archaeological.
Meacham: I think that can get us started on an interesting concept. In 2010, Chris, Fred, and I, Beto Nava, as well and Franco Attolini and Danny Riordan and Roberto Chavez, all did our underwater archeology course here in Mexico with the Nautical Archeology Society that was supported by the National Institute of Anthropology and History (INAH). It empowered us.
And by having that NAS certification, it kind of helped check a box for the Institute. And, you know, they could say if anybody questioned our abilities, well, we’ve got the certification.
I’d say the genesis of this for all of us here was the Hoyo Negro project, and with the exploration followed by the high grade survey, and then the photogrammetry, which is another whole level in itself. The major problem in Negro is the pit itself—it’s just immense—and how do you document something like that? So we worked with Beto and the team who came up with a grid system at 34 m/110 ft depth, and then it’s every 0.8 m/2.5 ft with a cookie on the line, and so it’s a systematic grid. The difficulty there is that it’s not just a nice flat bottom, it goes from 40 m/130 ft to about 55 m/179 ft, and it just becomes really complex.
But basically what I’ve been doing there is assisting with the lighting or helping Beto. So when we jump forward to doing the mine, it’s a completely different environment. There’s no pit—it’s a continuous cave—so there was no way we could put in a grid, and I’ve never really done photogrammetry before. I had observed it being done, but I was starting from scratch in terms of my own experience. So it was a challenge, but I had plenty of people to go to as resources, and who could check out what I’d done and help make it better. And what’s interesting about the big model is that you can see my progression as we go around, and now of course I want to go back and do it all over again.
So in terms of the challenges, I bought a Sony A7S camera and a Nauticam housing for it, and we just went in and started taking a bunch of photographs, came back, and put it into Agisoft. I have to say my expectations were low, but we were all pleasantly surprised when the model came back. This is like, “Wow that’s what we’re actually seeing there,” and it’s so cool. So that gave me the confidence to say, “I think I can do this,” and we basically picked about 250 m/817 ft of cave passage, which is a great example of the mining activity and of seeing what people were doing there.
That sounds like quite a learning curve, and a big challenge.
Meacham: Yes, we just started going in and piece by piece doing sections of the cave. I can’t remember how long in total we were down there. I’m sure it’s written down somewhere, but we took something around 18,000 photos. And as you know, taking the photos is probably the easiest part. Having the computing power and post-processing of the images is the key. A lot of people treat Agisoft as a bit of a black box, but you know it’s garbage in, garbage out. So in terms of the environment, we’re talking about a ceiling height that’s minimal, and while you can fit through OK, you want to be as high as possible for the photogrammetry in order to cover more area.
“I’m sure it’s written down somewhere, but we took something around 18,000 photos. And as you know, taking the photos is probably the easiest part. Having the computing power and post-processing of the images is the key.”
So, we just worked section by section, using the line as a reference. I was going down the line and started by making sure that I got any markers on it, and then going back and forth to get all the photos. The person that suffered the most was whoever was assigned to dive with me, as they just had to sit there and watch me go back and forth while taking the photos.
18,000 images! That’s a whole lot of processing.
Sam Meacham: Yes, we’re lucky to have the guys at University of California at San Diego (UCSD) helping us with the processing. I probably started off taking too many photos, but the computer guys complimented us on the photos and the overlap and coverage.
So what about other survey techniques, was there anything special about mapping this site?
Devos: We surveyed the first part of the cave, and that was pretty normal, but once we found the mine, then suddenly we had a need for all these new types of symbols that didn’t exist before for cave survey. I tried to think about what would be interesting to make notes of, but I didn’t want to speculate as to whether something was a natural pit or whether it was digging.
So we came up with three new symbols. There was already a symbol for a pit, but we added a jagged line on the pit to show that there was a broken edge, so it was smashed. Then we came up with a symbol for a displaced object, so if you see some stalactites and there was no way it came from the ceiling above, then that’s a displaced object. And then if you have stacked objects, so objects placed on top of each other, we had a symbol for that. We then made all of these colored red. I chose red because of the extracted material, the ochre. Also, when you look at the map, and you see all that red, it really shows the extent of the manipulation of the cave. It really brings it out, and I think that’s the most important thing about this cave. Sidewall information is nice, but this is very much an archaeological site.
So what’s next with the site? Any further diving plans?
Devos: We have some plans in place. The map that we’ve made, the photogrammetry, and the video documentation, even the exploration are not finished. So we actually concentrated on one area and tried to get that in the bag, you know, and focus our studies and our samples in that area, without stretching too far, but there’s still a huge portion to go. The technology really helps here, because you can bring that information out for the scientists and others to see. And then there’s much less need for others to go back there.
And this is really the part where we don’t know what’s going to happen. Are divers one day going to be able to go there to tour this site? Luckily, I’m not the one who will be making that decision; there is an archaeological department in Mexico who set the rules. But these conversations are starting, and we’re not really sure where they will lead. But for now we are doing what we can to secure the documentation of the site and working closely with the archaeologists and the landowner.
So a last question: What would your advice be to a diver who is just starting out on their GUE journey, and who hears about this and other projects, and wants to one day join?
Devos: We have been running all kinds of projects down here for years: exploration, science, surveys. Come and get involved, and help out. Good basic training helps open up the door.
Meacham: Once you’ve trained and gained enough experience to become confident in whatever environment you’re interested in, then come and get involved. There’s great training with the GUE Documentation Diver program, Science Diver, Photogrammetry Diver, and Cave Survey where you can actually put these skills to the test. Everyone on a project is an important part of making it work. Obviously it becomes tricky when archaeology is involved, as there can be federal laws and regulations that restrict access, and so we can’t always put just anyone onto a site, but there are all sorts of projects within GUE to help develop those skills and get known by project leaders.
Le Maillot: Of course, project diving is what GUE has been known for since the very beginning. So I think making that initial step to take training with GUE is an important one in the right direction. That’s the starting point of understanding how we are organized, the procedures that we use, [and] the team aspects of all our diving. And then it’s about thinking about what you want to do.
“Of course, project diving is what GUE has been known for since the very beginning. So I think making that initial step to take training with GUE is an important one in the right direction.”
If you’re interested in wrecks, you have Mario Arena in Sicily or Richard Lundgren with the Mars project, and you’re naturally going to be headed down the Tech 1/CCR route. If it’s the stuff in Florida, or Bosnia, or here in Mexico, and the cave thing really rocks your boat, then that’s where the GUE cave training comes in. Then, as you progress with your tech or cave training, you will get to know divers who are involved in projects, and that could be your instructor. You know, if you come here to do some cave diving in Mexico, then Fred is going to mention a few things about survey and cave projects in Mexico and around the world. So that will start opening up a different perspective for you.
Watch a Video of the Mine on GUE.tv. (Requires a GUE.tv membership or signing up for a free trial)
For more information about the La Mina project, you can visit the CINDAQ website
Check out the CINDAQ YouTube channel
John Kendall is a GUE technical, cave, and CCR instructor living in the UK. Since he was a small child, John has been fascinated by the underwater environment and the possibilities of adventure, and he is grateful to GUE for helping him to turn those childhood dreams into reality. As an instructor, John regularly travels around the world teaching GUE classes and helping to build local GUE communities. For the last 5 years, John has been working with underwater 3D Photogrammetry as a technique for nautical archaeology. This cutting edge technique allows for digital 3D models to be created of shipwrecks and caves, and allows researchers and scientists unparalleled abilities to manipulate and navigate the sites from the comfort of their own computers. John was the primary author of the GUE Photogrammetry class. He is also a member of the GUE Training Council and a Fellow of the Explorers Club.
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