Japanese Suicide Divers of WWII

Suicide divers for Japan during WWII? And no, I'm not talking about the airplanes, I'm talking about guys in the water. And, it wasn't only a concept, it was one that Japan actually used for devastating results for all involved.

For anyone who has ever been involved in a war or peace-keeping mission, it can be a scary place to be. I've not been in one, but I do have respect for the people involved in wars - including the poor civilians.

Now... you would think that in any war, the goal is to win... and win while surviving. There's no point in you, the soldier, having your country win a war if you aren't around. But the Japanese--driven by a fanatical devotion to the Emperor during World War II, were willing to do whatever it took--including sacrifice of their own life—to kill the enemy.

Hey... I know there's nothing wrong with your actions directly saving someone else... but to willingly give it up to kill someone? Yeah... suicide bombers... 9/11... Japan's Kamikaze (Divine Wind) pilots who would be equipped with enough fuel in their planes to get to the target, but not enough to get back home. As well as having some ammunition, the Japanese pilots would have a single bomb that they would use to drop on enemy ships in battle within the Pacific Theater. Once the ammo and bomb was used, the pilot would then attempt to ram his airplane into a ship.

Desperation breeds tiny monsters.

And, if you think that's some supreme devotion, you should learn about the Japanese suicide divers... the Fukuryo (伏龍, which translates to 'Crouching Dragons').

The Fukuryu were Japanese divers as part of its Special Attack Units trained to protect the homeland from invasion by the Allied forces. Training for the Fukuryu took place off Yokosuka-shi in Kanagawa-ken, just south of Tokyo in Tokyo Bay.

Take a look at the image above... we're talking about a guy in a diving suit... now picture him holding onto a five-meter (16-foot) bamboo pole equipped with an explosive mine containing 15 kilograms (33 pounds) of TNT(trinitrotoluene). Can't picture it? Hang on. Here you go:

A statue at a Yushukan Tokyo war museum depicting a Fukuryu suicide bomber holding a mine and lance.

Essentially, the Fukuryu would slowly dive under the water and jab the hull of a passing enemy ship triggering the explosive that would hopefully rip a hole in the ship and definitely kill the Japanese diver.

The whole diving suit consisted of a diving jacket and trousers, diving shoes, and a diving helmet fixed by four bolts. They were typically weighed down with nine kilograms (20 pounds) of lead weight, and had two bottles of compressed air at 150 bars. The divers also had a flashlight and a wrist compass.

This isn't something you swim around in at any great speed... these Fukuryu were expected to be able to walk at a depth of five to seven meters (16 to 23 feet), for about six hours - though there are reports that one could walk at a rate of two kilometers per hour (1.24 miles per hour).

According to documents found (not by me!), the Fukuryu diving suits utilized a circular breathing system with the air containing only 23 per cent oxygen... and when oxygen was spent, it was replaced by the two steel bottles holding 3.5 liters (0.92 gallons) of compressed oxygen, released to the suit via a valve-pressure device.   

The exhaled carbon dioxide was released after passing through a calcium-oxide purifier cartridge that would not release any tell-tale bubbles to the surface.

While some 1,000 suits were completed, and additional 10,000 were ordered - but never delivered as the war cut production off.

It looks so easy when the Japanese draw what's supposed to happen...

The diving suits had varying effectiveness (IE safety effectiveness) for the diver depending on length of time under water and the depth of water they were in, with reports suggesting the oxygen breathed would become 'poisonous' if submerged greater than 10 meters (32.8 feet). These are people on a suicide mission... they expect to die...

I assume that waiting for an enemy ship to pass by must be powerful tough work to make one absolutely famished, so Japan created a liquid food enabling a diver to eat underwater via a small hose. I have no idea what happens if you have to pee or poop, though I suppose the filter would be able to help the emission of a fart bubble or 12.

Exact numbers of people who were Fukuryu are not know, but estimates indicate that 4,000 men were in the special attack unit.

 This new weapon is only known to have been used a few times operationally:

• January 8, 1945: Damage by suicide divers to US Infantry landing craft (gunboat) LCI(G)-404 in Yoo Passage, Republic of Palaus in the western Pacific Ocean.
• February 10, 1945: Attempted attack by suicide divers on US surveying ship Hydrographer (AGS-2) in Schonian Harbor, Palaus.

So... actually, it looks like there were two official attempts - that we know off. While there was damage to at least one of the boats, it does NOT appear as though appear as though any Allied personnel were killed.

Did the divers die during the attempt? We'll never know. However, it is known that 10 people died during training while at Yokosuka owing to malfunctions of the diving apparatus and possible premature explosion of the mine. I hate when that happens. Actually, it's never happened, but I couldn't resist the joke.  

Now, contradictory to facts that I found, the US after the war got its hands on some of these Fukuryu weapons and made its own analysis... see image immediately above. According to detailed drawings, the weapon was a sort of lance mine - the Type 5 attack mine. It was drawn out as being 3.3 meters long with a 56 centimeter long sheet metal container holding a 10 kilogram (22-pound) TNT charge. The rest of the container was empty and used as a floating chamber. It was ignited by a 12 centimeter (4.7-inch) long horn fuse very similar to, if not the exact same fuse used on sea mines.

According to translated documents found, "the tested safety range between each diver was approximately . 60 meters (196.8 feet)".

Other records detailed that the Japanese special attack forces should construct submerged concrete installations and utilize sunken ships with an added diver chamber and it should be equipped to hold several divers and hold food, water and oxygen bottles. Of course, that sounds like a pipe dream and desperation of a warring faction knowing its days of war were at an end.

For a look the US report from 1946 on the Fukuryu weaponry, click HERE.

That's all for now. Next main article will take a look at Japanese rocket planes.