WWII Japanese Midget Submarine discovered

By Peter Fields + Photos from the book Japanese Submarine Raiders 942 A Maritine Mystery by Steven L Carruthers

The finding of M24, the missing third midget submarine which attacked shipping in Sydney Harbour on the night of 31 May 1942, has stirred a lot of memories of those wartime days and how close Japan’s war came to Australia and New Zealand.

In February 1942 Admiral Yamamoto dispatched the large float plane-carrying submarine I-25 (108.65m -356.5 ft long) to reconnoitre targets in eastern Australia and New Zealand. Her one-man plane carried out a three hour reconnaissance over Sydney harbour before rejoining the sub which then continued south to repeat flights over Melbourne and Hobart. It also did reconnaissance flights in New Zealand, flying over Wellington (8 March) and Auckland (13 March) looking for possible Allied shipping targets.

Later, in April, the Third Submarine Company under Captain Hankyu Sasaki was dispatched from bases in Truk Lagoon and the Solomons to reconnoitre and attack. The fleet consisted of five I class submarines I-22, I-24, I-27, 1-21 and I-29. Three carried on their hulls a midget submarine and I-21 and I-29 housed two float planes. The I-21 under Sasaki had another look at Auckland in mid-May but fog prevented any sighting of Allied shipping. When flying over the Auckland airfield at 400m (1,315ft), landing lights were switched on to assist his landing. The New Zealanders thought he was a friendly aircraft!

The sub fleet then assembled off Sydney and sent three midgets to attack the harbour. Two (M-24 and M-27) were detected by the Loop Station whose purpose was to detect metal objects coming into and out of the harbour, but the signals (signatures) were disregarded at the time! The M-22 was spotted before passing over the loop and was destroyed by depth charges and M-27 became entangled in the harbour’s anti-submarine nets. M-22 was spotted in the harbour and was eventually destroyed by depth charges. M-24 fired two torpedoes at the US cruiser


, both of which missed but one exploded against the sea wall at Garden Island directly below the converted ferry


killing 21 and injuring 10 sleeping naval ratings, some of whom were New Zealanders.

Midget M-24, with its two man crew, Sub-Lieutenant Katsuhisa Ban and Petty Officer Namori Ashibe, evaded its hunters and slipped out of the harbour and into an historical mystery as they did not rendezvous as expected with their mother submarine I-24.

Over the years many people (even Dive Pacific’s correspondent Dave Strike who led a hunt – well publicised – in 1975) have searched for M-24 and myriad and fanciful theories as to its whereabouts have been propounded. Several spurious sightings/findings created press interest and films but the sub’s whereabouts remained a mystery.

In the 1990s John Riley and I spent many hours in research and pursuit of this elusive submarine. We magnetometer-searched great swathes of Sydney Harbour and targeted some wrecks which seemed likely but which turned out duds. Recent-time sophisticated sidescan sonar sweeps of Port Jackson showed definitely it was not in the Harbour and a wartime magnetic loop at the harbour entrance seemed to indicate Ban and Ashibe had indeed escaped the port in the early morning following the attack.

There’s a bunch of divers on Sydney’s North Shore who call themselves

No Frills

, real knockabout blokes who dive weekly out of Long Reef. They get their name from their habit of dressing, dive-wise, in 1970’s outfits. single tanks, disdaining BCs or any of that fancy modern frippery, and you have to be over 70 years old to wear a sissy drysuit.

They’re notorious for growing old disgracefully. A 70 metre dive, on air, on the

President Coolidge

for example followed by the consumption of a slab of beer then an afternoon 70 metre dive on the


again is in their repertoire. They’re friends of mine and we’re often diving the same places. Their method of accurate anchoring on a 50 metre deep wreck is for one of the party to jump overboard with anchor and chain carried in his arms, taking it directly to the target.

On one of their regular weekend diving trips during 2006 seven of their crew: David Arnold, Paul Baggott, Tony Hay, Phil Hendrie, Greg Kearns, David Muir and Alan Simon were north of Sydney Heads when their echo-sounder revealed a new anomaly on sand in 53 metres of water three miles off Newport Beach. They returned on 12 November 2006 to investigate. Voila – a long cylindrical thing with contra-rotating props on one end and a conning tower, the whole covered by a trawl net. The mystery was solved.

They were forever to be cemented into Australia’s maritime history.

An Overview by Dave Moran

In the recently published book about the midget submarine’s attack:

Japanese Submarine Raiders 1942, A Maritime Mystery

by Steven L Carruthers, I highly recommend this detailed account leading up to the attack, the attack itself and the postmortem.

Steven writes:

The discovery has been described as the most significant modern marine archaeological find ever in the Pacific since the discovery of the Titanic in the



He was not commenting on the most recent midget submarine to be discovered just north of SydneyHarbour but about the discovery of the fourth midget submarine. It was one of five that attacked Pearl Harbor in support of the Japanese’s aerial bombardment on 7 December 1941.



The discovery of M-24 has, in contrast, been in many ways under-reported by the general media. Exclusive media agreements with a few major players and with some restriction for only releasing in Australia has meant that divers in New Zealand and, I guess many around the world, have largely missed this major maritime discovery.

The Australian television programme 60 Minutes on Channel 9 ran an exclusive interview with the divers on 24 November 2006. To view the video clip of the 60 Minutes interview visit:


click on Related Links – 60 Minutes exclusive video.

Reporter, Liam Bartlett also conducted an interview on 60 Minutes’ Online Chat room with divers Paul Baggott and Alan Simon. Visit:


They described how, four months earlier their

No Frills

diver group’s sounder had picked up a lump on the bottom but had not investigated it until their dive on 12 November.

What they found on a sandy bottom was a cloud of fish above a net hanging off a cylindrical shape. Then they saw the unmistakable conning tower and twin counter rotating propellers and the submarine’s net cutter blade clearly visible, lying beside the hull, they could hardly believe their eyes – their hearts were racing!

They all knew the history of the M-24 and of the numerous searches and ‘finds’ that had been reported over the last 64 years. Wreck diving they loved but could this be the ultimate find even though at the time the M-24 was just about the last thing on their minds! The divers all admit that Lady Luck was smiling on them that day!

Navy divers inspected the wreck and after taking measurements and noting the vessel characteristics and comparing them with the known specifications of the Ko-hyoteki (Type ‘A’ Target) midget submarine, they verified that the weekend divers had discovered the M-24.

The divers consider that a fishing trawler net has ripped the hatch off and that the two crew remains are still trapped inside the submarine.

The divers have not attempted to penetrate the wreck and reported that the hull appears to be full of sand to just below the conning tower. You can see the periscope tube, a ladder, cogs and the batteries whose acid appears to have caused some corrosion with large gaping holes in that aft area.

Since the find there has naturally been interest by the relatives of the crew as to the possibility that their loved ones remains may still be within the sub.

Further diver investigations have revealed that the two-rung entry and exit ladder is in the up position which would indicate the crew’s remains are still inside.The brother of Sub-Lieutenant K Ban has requested that the submarine be left in peace.

The sister of Petty Officer N Ashibe would like the submarine recovered and her brother’s remains returned to Japan.

As we go to press, the Japanese government has yet to decide if a request should be formally made to the Australian Government as to what action it would prefer.

The site has not been declared a war grave. It is interesting to note, that according to the Australian War Graves Commission, no ship in Australian waters can be declared a war grave.

It will be interesting to see how the Australian Government handles the preservation of the site and what the Japanese Government may wish to happen to the site and the crew’s remains.

Will it remain on the bottom or will it be recovered?

If left on the bottom, it will become less and less protected as time passes and could eventually be targeted by ‘collectors’.

It is hoped that in the future, pictures of the M-24 become more readily available for the public to view and for magazines to publish without incurring large publication fees.

Like all divers the discoverers,

No Frills

are now not allowed to dive the wreck, but they hope that in the future they may be able to be involved in any recovery operations if that was to occur. Which when you think about it, they should be asked.

Government agencies need to encourage the possibilities of the amateur wreck diving enthusiast being involved in any historical wreck they find. I’m sure the wreck diving community will be watching with interest to how the

No Frills

divers are treated by the various Government agencies!

Anyone for a night dive? Sorry no torches allowed!

Midget submarines that attacked n Sydney Harbor, specifications: Type Ko-hyoteki (Type A Target) fifty were built.

Displacement:46 tons submerged
Length: 23.9 m (78.5 ft)
Beam: 1.8 m (6 ft)
Height: 3 m (10.2 ft)
Ballast: 5,899 lb (2,670 kg) in 534 × 11 lb (5 kg) lead bars
Designed depth: 30 m (100 ft)
Propulsion: 192 trays of two two-volt cells each,136 trays forward,56 trays aft;one electric motor, 600 horsepower (450 kW) at 1800 rpm,two screws conter-rotating on single shaft,leading prop 1.35 m diameter, right-handed;trailing prop 1.25 m diameter, left-handed
Speed: 23 knots (43 km/h) surfaced,19 knots (35 km/h) submerged
Range: 100 nautical miles at 2 knots(190 km at 4 km/h),80 nautical miles at 6 knots(150 km at 11 km/h),18 nautical miles at 19 knots(33 km at 35 km/h)
Complement: 2
Armament: 2 × 18 in (457 mm) torpedoes muzzle-loaded into tubes,one 300 lb (140 kg) scuttling charge.

Australian Government moves quickly to protect the wreck site.

The M-24 site was declared a provisional Historical Shipwreck on 27th November 2006 under the Historic Shipwrecks Act 1976. The Federal Minister for the Environment and Heritage declared a 500m radius Protected Zone on 1st December 2006.

The site is now protected under the Historical Shipwrecks Act 1976.

Also on the same day the NSW Government announced that fines of up to $1.1 million or up to six months’ jail for anyone caught damaging the site.

Divers should also be wary! Within the hull, fore and aft of the battery compartment are demolition charges. Their condition is unknown!

The exact location of the protection zone is bounded by an imaginary line forming a circle with a radius of 500 metres the centre of which is at the intersection of the parallel 33° 40’ 21” South latitude with the meridian 151° 22’ 58” East longitude.

Visit: www.heritage.nsw.gov.au/09_subnav_02.htm

For further information of Japanese submarines visit: www.answers.com/topic/imperial-japanese-navy-submarines

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