Forbidden History - Chuuk Lagoon: America's Retribution for Pearl Harbour

Episode Date: May 5, 2026

In this episode of Forbidden History, we dive beneath the surface of Chuuk Lagoon, where a vast underwater graveyard tells the story of one of World War II’s most devastating naval defeats. Exploring the remains left behind after Operation Hailstone, we uncover how these wrecks became both haunting relics of war and one of the most extraordinary dive sites on Earth. Cast List: Eric Meyers: NarratorProfessor Bill Jeffrey: Maritime archaeologist, University of GuamDiane Strong: AuthorGradvin Aisek: Local historian and cultural commentatorJim Pinson: Technical diverBill Stinnett: Author and WWII naval researcherGuy Walters: Historian and authorMichael Barnette: Maritime archaeologist and wreck diver Learn more about your ad choices. Visit megaphone.fm/adchoices

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Welcome to the Forbidden History Podcast. We're an independent podcast. and advertisements help keep us going. Ads are automatically placed and not specifically chosen or endorsed by us unless read by me the host. Thanks for supporting the show. Beneath the waves of a lagoon in the South Pacific

are more than 60 shipwrecks. Bombs, bullets, beach mines, all sorts of other highly explosive products on board. It's a miracle. It wasn't vaporized during the attack. Most have been well documented. But one underwater explorer now believes that he has evidence of an unknown wreck which may rewrite the history of what happened here. Came across something that was not known to be in that area.

It's a bit of a mystery because we don't have records of any ship being there. What will they discover? And will it reveal the lost secrets of what has become known as the Japanese ghost fleet? Something blew up around here, I think. The seas and oceans of the world are filled with mysteries, lost ships and lost lives. More than 1,200 miles from the nearest continental landmass lies Micronesia. It's a country comprised of four island states called Khosr, Pompay, Yap, and Chuk. The atoll of Chuk is home to stunning beaches, crystal clear waters, and one of the

the most incredible underwater graveyards in the world. After World War I, Japan assumed control of Micronesia. They had intended to run the islands peacefully, but soon realized that Chuk, known then by its former name, Truk, could be of vital military importance. Truck is the absolutely perfect location for a naval base. The Japanese saw it there, a slap bang in the middle of the Pacific and realize that's fantastic strategically. But better still, because it's a natural coral atoll, it's the perfect anchorage point for a massive fleet. It's got natural protection. But also what the Japanese do is to augment that with their own fortifications. But in 1944 came an attack by US forces on the island's

stronghold. More than 50 Japanese ships were sunk. many of which have since been explored and identified. In 2002, Professor Bill Jeffrey of the University of Guam was part of a project to record all of those known wrecks. When I did my research, I documented all the wrecks in the area. We were just sort of turning around and coming back towards another site, looking around with the side scan sonar, and then we came across something that was not known to be in that area.

It was obviously something not natural. was obviously a man-made feature. Now, Bill thinks he's found a mysterious wreck that all other explorers have missed. It's a bit of a mystery because we don't have records of any ship being there. As he dug deeper, Bill realized that there were many ships that are still listed as missing in action,

more than 80 years after the war. In my research in the National Archives in Washington and San Francisco, I did come across a list of of about 130 ships, smaller-sized ships, up to a couple of thousand tons, that are lost. Bill is now planning to return to the lagoon to do what no other explorer could.

Identify a mysterious sonar image. If we can dive, if we can sort of record what's there, we get some dimensions of it, get some identification through other things. We might be able to marry it up to a particular ship on this list. But diving an unknown wreck in the lagoon is not something to be taken lightly. The raid on truck saw the Americans make a devastating two-day attack,

and many of the Japanese ships that were sunk went down carrying explosive cargo. Ships like the San Francisco Maru. The San Francisco Maru is known as the million-dollar wreck, and there's a good reason for that. It's called the million-dollar wreck because it has that or more worth of munitions and supplies on board. The ship had managed to survive the first day of the attack, but on day two, she was hit by six 500-pound bombs, sending her to the bottom,

where her deadly cargo remains to this day. Seeing all this munitions on board, highly explosive material, it's a miracle that ship wasn't vaporized during the Allied attack. It's got cordite. It's got thousands of hemispherical. beach mines. And actually, if you dive today onto the forward deck, you can still see three Mitsubishi

Type 95 hargo tanks. They're right there. Why was this remote atoll singled out for such a large-scale attack? The answer lies in the years leading up to World War II when Chuk was governed by the Japanese. Gradvin Asik grew up surrounded by the ruins of Japanese fortifications and listening to the tales of the local elders. The Japanese educate the people of Chuk, and they hired them to work for the Japanese. And the Japanese really helped the local people. They feed them, they give them what they want, and they pay them.

Turkey's people that were there in those early days, they said it wasn't too bad. They had all sorts of facilities there, ice cream parlours, a cinema. Before the war started, some people thought that life wasn't too bad, even though it was under quite stringent Japanese control. Perhaps the unique perspective of the islanders can help solve the mystery. the wreck won't be easy. So many are littered here, and they all stem from one world-changing event. On December 7, 1941, Japan launched a surprise attack on a U.S. naval base in Hawaii. People talk about turning points at the Second World War. Believe you me, Pearl Harbor was the

turning point. Truck was now a battleground, which would eventually see the sinking of the Japanese fleet. In the remote Pacific Island of Truk, underwater explorer Bill Jeffrey is hoping to identify a mysterious sonar image. The origins of the story are rooted in the notorious attack on Pearl Harbor. As the war progressed, life for the islanders changed. The Japanese became cruel occupiers. The people of Chuk, they work with the Japanese. The Japanese treat them like slave. They forced them to work without get paid.

Chuk was gradually turning into one of the most important Japanese bases in the Pacific. Truck is not only this fantastic anchorage point for the Japanese 4th Fleet, it's also a major place where you can ship supplies and goods in the fight against the Allies. It's got four airstrips and even a C-Port. playing base. This is a serious, serious fortification. Eleven years after his initial discovery, Bill returns to Chuk Lagoon, his mission to finally identify the mysterious sonar anomaly. This time, he's joined by professional diver Jim Pinson. As Bill and Jim discussed the plan for tomorrow's dive, they stand on the same

shoreline that witnessed the sinking of more than 50 Japanese ships. Their wrecks are scattered around the island. During the Battle of the Pacific, Truck had become a real concern to America. Reconnaissance missions were showing the full extent of the fortifications on the atoll. But there was something else. Truck was also harboring Japan's largest top-secret weapon. Even before the war began, Japan had embarked on an ultra-secret project to create a weapon designed to counter the American force.

fleets greater numbers. Two B-24s from the Air Sal's command came in on reconnaissance. It was a very cloudy day, and there were destroyers and all kinds of military ships. But they did see the Yamato, and they couldn't believe they'd ever seen anything that big. It was astonishing. Yamoto was not just the heaviest and most powerful ship ever built. She also represents this huge symbol. She represents the Japanese Navy's might, her technological power, her ability to absolutely trounce any opposition.

This is a really attractive target for the Americans. Bill and Jim know exactly where the wreck of the Yamato is, but their interests lie further out in the lagoon. The simple fact was that the threat to U.S. operations in the Pacific could no longer be ignored. It would eventually lead to the attack that sunk the Japanese ships. Among them was the mystery wreck which Bill and Jim are now determined to identify. The attack was given the code name Operation Hailstone. You have this unit called Force 58 under the American Admiral Mitchell, and he is going to use this to attack Truck.

This is a massive operation. Bill and Jim's first dive takes them to the location that was at the heart of that attack and is still littered with the weapons and bombs of that bloody day. On the island of Truk in the Pacific, explorer Bill Jeffrey and diver Jim Pinson are on a mission to identify strange wreckage from one of the greatest U.S. naval attacks in the war. Although the reasons are shrouded in secrecy, In February 1944, the Japanese came to believe that a U.S. attack was imminent and evacuated their main fighting ships from truck.

They left behind many working ships, cargo vessels, and merchant freighters. It was these ships that would face the onslaught of Operation Hellstone. U.S. Task Force 58, with its destroyers, aircraft carriers, cruisers, submarines, and warplanes, was now headed towards its target. Just before daybreak on February 16th, the order was given to attack. Bill Jeffrey, who is on truck today preparing to search for mysterious wreckage from the attack,

takes up the story. They all would have had their mission about what to bomb, the 19 islands, and many of them have military facilities. Bill has learned that there was one wrecked ship sunk during Operation Hailstone that was only discovered in the 1980s. Mysteriously, neither that ship nor its cargo turned out to be Japanese. So what was it?

The Hokie Maru was originally called the Hauraki, and in fact she wasn't originally a Japanese ship. She was actually built by the British and then actually owned by a New Zealand shipping company, and the Japanese actually captured her when she was sailing from Fremantle to Colombo. Bill's research shows that the vessel was taken to Yokohama, where it was modified and was renamed the Hokie Maru. The Hokie arrived at truck with its cargo of supplies just weeks before Operation Hailstone. She was sunk on the first day of the attack. Bill Jeffrey has discovered that the wreck lies in 170 feet of water, just east of what is now, Doblon Island. and that previous dives have revealed that much of its cargo remains intact.

But most intriguing of all is what was on board. Two John Deere tractors, both designed and manufactured in the USA. But for Bill and Jim, the great prize is to find what that sonar blip actually is. As they pieced together the clues, they've found that truck was once the possible target for a very different and far more deadly kind of attack. During a meeting held on May 5, 1943, members of the Military Policy Committee discussed a top-secret weapons program known as the Manhattan Project.

A key part of that was Truck Lagoon. Long before the Americans dropped the A-bomb on both Hiroshima and Nagasaki, it was actually the atoll of Truck was considered the perfect place. to test this new deadly weapon. So what the Americans wanted to do was to see what effect the atom bomb would have on ships. The plan to drop an atomic bomb on truck never materialized. But the U.S. later carried out a controlled test

at another South Pacific Island group, Pekini Atoll. It gave a chilling glimpse of what lay in store. Visit BetMGM Casino and check out the newest exclusive. The price is right. fortune pick. BetMGM and GameSense remind you to play responsibly. 19 plus to wager. Ontario only. Please play responsibly. If you have questions or concerns about your gambling or someone close to you, please contact connects Ontario at 1-866-531-2,600 to speak to an advisor, free of charge. BetMGM operates pursuant to an operating agreement with Eye Gaming Ontario.

In Toronto, every arrival is a statement, and nothing says it better than this. Cadillac Optic was the number one selling luxury EV in Canada for 2025. Find your rhythm across a seamless 33-inch display and an immersive 19-speaker AKG surround audio system. This city demands agility and optic delivers with precision to make every drive extraordinary. Let's take the Cadillac. Find out more at Cadillac Canada.ca. Luxury sales claim based on S&P Global Mobility Canadian New Vehicle Total Registrations for calendar year 2025 for the Cadillac definition of luxury. Operation Hailstone may have been this incredibly violent all-out assault on truck,

but actually as of nothing compared to what would have happened had this memo being followed, and truck was nuked. Since the first wrecks were discovered here in the 1960s, the continued interest in diving the area prompted Gradvin's father, Kim Yu, to open up Chook's very first dive resort, the Blue Lagoon. In the years that followed, many new wrecks were found and identified. If so many wrecks in the lagoon have been discovered, how has it managed to remain a secret for so long? How were they missed? And what part do they play in the truck lagoon story?

There is only one way to find out the answers. Bill and Jim now know they need to dive it. So it's back to the Blue Lagoon to suit up. The sonar hit was 230 feet below the surface. Jim will need to limit his time at the bottom to allow him to re-compress as he surfaces, avoiding nitrogen build up in his blood, which could give him the bends. We're going to spend about 30 minutes on the bottom,

but we might spend up to two hours coming all the way back up. But at those depths, the bends are not the only danger. Narcosis is not a possibility. It's a fact. You're going to get narcosis at the depth we're going. Deeper you go, the more narcosis, just like drinking more alcohol. Problem, your body has a fight or flight reflex. That makes an narcotic effect even more.

So the narcosis could be not a problem until something went wrong. Then it's a very big problem. A little bit of concern for anything that goes on like that. So a little bit more than the average diving. Jim will also have to be especially vigilant diving any new and uncharted wreck site in the lagoon. As many of the ships were carrying explosive cargoes, much of which are still live. The locals, when I first came here 42 years ago, they would take mines and use it to dynamite fish. It's really dangerous to go into these underwater historic items, and you just have to pay it.

attention. And as with any unfamiliar wreck, diving can present a whole host of potential risks. You don't enter into a place when you're underwater, you can look in and you'll see light coming out from somewhere, and that's you're out. The real danger is silting up. Silting up happens when fine sediment is disturbed during a wreck dive. It can cause completely complete loss of visibility and orientation, which can have fatal consequences. I've been involved in recovering three dead bodies,

divers that died while diving. One person, he got into a very narrow place. It silted up, and when we found him, his air, his tank was dry, his regulator was still in his mouth, and he just didn't make it. With final checks complete, and their equipment loaded onto the boat, It's time to head to the wreckage.

This is Tonnewus. It's the main island during Japanese time, and we're heading around the northwestern part of Tonowus and going out probably in a northeasterly direction for about a kilometer. On the way to the mystery wreck, Bill passes over another stark reminder of why the U.S. saw the assault on truck as revenge and retribution. Japanese submarine I-169 had been an important. part of the attack on Pearl Harbor. It managed to get into the harbor and launch five mini-subs that went on to destroy two U.S. battleships.

She's got this enormously impressive military track record, and not only that, she also survives Operation Hailstone. So she's an incredibly lucky sub, but of course that luck is going to change. When Bill and Jim arrive at the wreck site, whatever that strange blip is, will be directly below them. In Truck Lagoon, maritime expert Bill Jeffrey and diver Bill Pinson are on a mission to

identify a mystery sonar image, which could be an unidentified wreck from Operation Hailstone in 1944. Staples Preferred Business Membership, built for busy business owners, because you've got bigger things to think about. With Staples Preferred, get free delivery, no minimums. Staples Preferred unlocks up to 3% back. Plus 10% savings on print and exclusive wireless offers. One less thing on your plate.

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They're called fans. Fans don't just listen to music. They feel seen by it, like it belongs to them. So when your brand shows up on Spotify, that's who you're talking to. And you're right next to artists like me, Lizzo. So, are you ready to talk to fans? Spotify Advertising, you're among fans. Bill wonders if it could be connected to a Japanese submarine

and a very dramatic story. After Operation Hailstone, those Japanese vessels that had survived the internet, attack were on constant high alert. And on April 4, 1944, submarine I-169 received the message all aboard had been fearing. B-24 bombers had been spotted in the sky, triggering an air raid warning to avoid them. I-169 made an emergency dive, but in their panic, the crew had left the ventilation valves open. Water flooded into the control room. The 14th, the 14th, the four 100-ton submarine with a crew of 80 were now trapped at the bottom of the lagoon with limited air and little chance of rescue.

But suddenly, there was a glimmer of hope. Rescue divers were sent down to the sunken submarine and signaled to the trap crew by banging on the hall. After confirming that there were still survivors, a rescue mission began to bring the trap crew members to the surface. These cables start winching this submarine up. But as the submarine broke the surface with the crew, just moments away from salvation, disaster struck. The added weight of all the flooded compartments snapped the cables. Divers go back, bang on the side of the hull, and this time there is no reply. Jim dives, and on deck, all Bill can do is wait.

As the light fades, so do Bill's chances of finding anything. Yeah, I think he would have signaled to us in some way that we'd found something. Jim had only planned to spend 20 minutes at the bottom before sending up a float to let the crew know that he's beginning to resurface. 24 minutes. Oh, it's getting close to dark, isn't it? Over 40 minutes have passed, and still no sign of Jim. Finally, Jim signals to let the crew know all is well.

It came up a long way off the wreck. So if it found something, I think he would have come up a lot closer. Sometimes you win him and sometimes you don't. They'll have to wait for him to finish his recompression to find out if he's made any discoveries. I mean, obviously you, you guys want to know, did I find it? Yeah. I didn't see anything in the first like 15, 18 minutes.

It's only after about 20 minutes in the dive. That is when I started seeing things. I found an anchor in at least three parts. I don't know how you break an anchor. I mean, literally, this was broken. I found what looked to be part of a hole plating or something that was probably 12 feet across, blown through the middle, like an explosion, it ripped the metal open.

So something blew up around here, I think. Bill and Jim seemed to have found evidence of a sinking in an area where no ships are known to have gone down. Could the dive team have discovered an as of yet unknown victim of Operation Hailstone? What will a review of Jim's new wreck footage reveal? The day after the dive, Bill Jeffrey and Jim Pinson meet to review the footage. Did the mysterious anomaly found on Bill's son, found on Bill's sonar scan match what Jim discovered on the ocean floor. Nothing had occurred. What I saw in the water on the dive was not that.

100% not that. There might be some more stuff out there. History is still a mystery. We probably have two different sites. Solved one question by adding another question, basically. We've got two questions. Now we have one question. Now we've got two questions. We're making progress. So if the wreckage found in the lagoon was not what was seen on the scan, what was it? And where did it come from? The first thing that I ran into, so I wanted to see what it was exactly,

because I wanted to see if it was something metal, and of course it was. This is an anchor, but it's not an anchor. It's part of an anchor. And I've never, ever seen a broken anchor before. That's a good find. Well done. This was what got me the most excited. It looked like just some twisted metal, and that's actually what it is.

This is heavy-duty metal, thick gauge, and it is just curled up all over. Looks like it was blown out this way from an explosion. I think it's all one piece. You can't see most of it because it's buried in the sand. What you found looks more like debris. Yeah, it's evidence of some of it. massive force, massive force.

Because that metal is curled over. It's not just blown like this a little bit, it's curled over. Seemed to be in the direction of where IKoku was. The IKoku Maru was an armed merchant cruiser of the Imperial Japanese Navy, sunk during Operation Hailstone. Since its discovery over 40 years ago, a question mark has remained over the mysterious whereabouts of its missing bow section. missing bow section. If what Bill and Jim have discovered really is part of the missing

bow, why has it been found so far away from the main wreckage? They've found parts of the bow, little bitty parts of the bow up to 200 feet away, but you know, we're quite a bit further away. Using the GPS coordinates, Bill has calculated that the debris found on the dive was over 650 yards from the main wreck. Just how would have been possible for large chunks of metal to travel that kind of distance. The answer may be supplied by an eyewitness who watched from the shore. On the first day of Operation Hailstone, instead of heading for cover, Kimmy Yu made his way to the beach and watched the devastation unfold.

And he just stayed there on the shore watching. He just was so much in shock, especially because he had worked on those ships. He saw ships running with smoke. He said that he saw the Aikoku. Kimi Yu watched as the Aikoku was struck by four bombs. Crippled but still afloat, she was attacked again, this time with a torpedo. She took a direct hit in cargo hole number one,

which was full of ammunition and high explosives. That's when he saw it disappear in a mushroom cloud. It lasted one minute and the ship was gone. The blast was so great that it had even destroyed the U.S. Avenger aircraft, which had launched the torpedo, killing all three of its crew members. This is more of a debris field that was lifted up and moved over by an explosion. Yeah, that sort of jagged middle. You saw a broken...

I mean, I've seen that on shipwreck. still attached. I've never seen it just laying out. So that could have been the piece, you know, piece of the whole plating that was just blown apart. The clues suggest that what Jim and Bill have found is part of a ship destroyed by a huge explosion. It was possibly the Aikokumaru. Even today, determined divers, ongoing research and modern technology can shed new light on events that took place here more than 70 years ago. and the lagoon that saw such destruction continues to give up its secrets. Thanks for exploring the past with us today.

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