Figure 1
A Japanese artwork depicting a Kohyoteki Type A midget submarine. Eight of these midget submarines were expended during the Guadalcanal Campaign, with seven still remaining as archaeological sites in the Iron Bottom Sound area. The Kohyoteki 30 archaeological site off Savo is still completely intact and an Archaehistoria Expedition in January 1999 attempted to locate it. [As published p.9 Gakken Vol. 35].

Author
Ewan M. Stevenson
28 April 2013

Location
Possibly sunk off Kalaka, South West side of Savo Island.

GPS
09º 9.080’S, 159º 47.200’E approx.

Crew
Lt.(jg) Teiji Yamaki and PO1 Ryoichi Hashimoto.

Specifications Kohyoteki Type A
Length overall (m)		23.90
Breadth, maximum (m)		1.85
Depth, conning tower to keel (m)		3.10
Displacement, submerged (tons)		46
Main battery (type/no of cells)		Special D/224
Main motor (hp)		600
Maximum submerged speed (kts)		24.85
Radius of action, submerged (kts/nm)		6/80 18/50 min
Safe diving depth (m)		100
Torpedo armament		Two 45.7cm (18-inch) diameter Type 97
Periscope, length (m)		3.05

 

Figure 2
General Arrangement of Kohyoteki Type A. [As published p. 117 of Warship 1993].

History
During the Guadalcanal Campaign, the Japanese maintained an observation post on the Eastern edge of the summit of Mt. Austen. From this OP, the Japanese looked down on the Marine perimeter and Henderson Field. In addition, American naval movements in Iron Bottom Sound were reported. The arrival and departure of American transports unloading supplies and re-enforcements at Lunga Point adjacent Henderson Field was duly noted and the information sent to higher command.

In response, the Japanese planned to use midget submarines (Kohyoteki Type) to attack the American transports. A midget submarine base was intended for construction in Kamimbo (Tambea) Bay near Cape Esperance at the Western end of Guadalcanal. However, as the campaign developed, American military pressure forced the Japanese to change plans and reduce the base to more like a “reception” centre (Site GUAD43). The Kohyoteki would be brought underwater to Iron Bottom Sound “piggy-back” style on fleet I-class submarines and then released at night for attacks. After the attack on the Lunga Roads area, the Kohyoteki would return to Kamimbo Bay, where the two man crew would abandon their Kohyoteki, and then swim and walk to the ‘reception’ centre. The Kohyoteki crews were later evacuated by fleet submarines.

The Americans used destroyers, destroyer escorts, sub-chasers, patrol craft, and New Zealand corvettes to form an anti-submarine and anti-aircraft screen around the transports and freighters unloading at Lunga Point. The escort vessels patrolled back and forth in a perimeter outside the transports listening constantly with sonar gear for interloping submarines. For the Kohyoteki, they had to penetrate this screen to reach an attack position on the transports. The compact size of the midgets was an advantage in penetrating this screen.

The Japanese launched eight Kohyoteki missions during the Guadalcanal Campaign. After launching, two of the Kohyoteki’s were forced to abort due mechanical difficulties. The Kohyoteki 30 (Ha-30), sunk off Savo, was one of this pair that frustratingly had to abort their mission. The remaining six attacked American shipping off Lunga Point. Half of these attacks were successful in torpedoing a ship. Co-ordinating these attacks with the arrival of American ships (targets) off the Lunga roadstead would have been very difficult for the Japanese.

The first Guadalcanal Kohyoteki attack was by Ha-11 on November 7, 1942. After being delivered by mother submarine I-20, Kohyoteki 11 found meagre pickings off Lunga Point- the single 5000-ton, 22 year old, freighter USS Majaba (AG-43) and two destroyers. The Ha-11 blew a big hole in the freighter’s side, which was beached to prevent her sinking. The Kohyoteki crew managed to sneak away and beach Ha-11 on the coast at the Western end of Guadalcanal (Site GUAD56; see also ‘Then and Now’ Section). This crew successfully made it to the reception centre at Kamimbo and were evacuated.

The second Kohyoteki attack in Iron Bottom Sound occurred four days after the first and is the subject of this report. Mother submarine I-16 deployed Kohyoteki 30 but the midget submarine experienced rudder difficulties and was forced to abort the mission. The Ha-30 was scuttled and “sunk off Savo” according to Japanese sources. The crew, Lt.(jg) Teiji Yamaki and PO1 Ryoichi Hashimoto, survived the mission and Teiji Yamaki was still living in Japan in 1994.

The only other ship torpedoed by Japanese midget attack during the Guadalcanal Campaign was the USS Alchiba (AK-23). The cargo ship was beached in Tenaru Bay after the first hit on November 28, and then had the misfortune to be torpedoed a second time by another Kohyoteki 38 (Ha-38). In the second attack, the Alchiba didn’t move- she was already beached! Both victims of Kohyoteki attacks at Guadalcanal were later salvaged, repaired, and returned to war service. Overall, the Kohyoteki operation results were poor for such a major effort by the Japanese and minimally disrupted the vital American logistics train into Guadalcanal.

Table 1. Japanese ­Kohyoteki Operations of the Guadalcanal Campaign and Archaeological Sites

Kohyoteki No. (Mother submarine)	Launch date from mother sub	Crew	Comment	Site
Kohyoteki 11 (I-20)	7 November 1942	Lt. (jg) Shinji Kunihiro PO1. Goro Inoue	Torpedoed USS Majaba (AG-43), successfully abandoned near Kamimbo	GUAD56
	Still there in good condition. Extreme risk of scrapping. Under grave threat of vandalism. See ‘Then and Now’ section.
Kohyoteki 30 (I-16)	11 November 1942	Lt. (jg) Teiji Yamaki PO1. Ryoichi Hashimoto	Aborted due rudder difficulties, scuttled off Savo	SAVO13
	Subject of Archaehistoria.org search Jan 1999 & Nov 2011. Undiscovered site. Likely 900-1200 meters depth.
Kohyoteki 37 (I-20)	19 November 1942	Lt. (jg) Toshiaki Miyoshi PO1. Kyoshi Umeda	Aborted due depth control difficulties, successfully abandoned near Kamimbo	FLOR15
	Salvaged by USCGC Ironwood (WAGL-297) January 1945. Known site awaiting survey by Archaehistoria.org; funding?
Kohyoteki 12 (I-24)	20 November 1942	Lt. (jg) Yasuaki Mukai PO1. Kyugoro Sano	Did not return	IBS34
	Have tried to historically link to American anti-submarine attack but so far failed; any ideas anyone? Site unknown.
Kohyoteki 20 (I-16)	28 November 1942	Lt. (jg) Hiroshi Hoka PO2. Shinsaku Iguma	Torpedoed USS Alchiba (AK-23), sunk by USS Lansdowne (DD-486)	IBS51
	Undiscovered site. In approx. 700 meters between Savo and Cape Esperance. Nearly made it to the reception centre!.
Kohyoteki 8 (I-20)	2 December 1942	Lt. (jg) Chiaki Tanaka PO2. Mamoru Mitani	Targeted SS Joseph Teal; nearly hit Alchiba. Successfully abandoned Visale	USA
	Salvaged by USS Ortolan (ASR-5) May 1943, now displayed at Nautilus & Submarine Museum, Groton, CT. Best preserved.
Kohyoteki 38 (I-24)	7 December 1942	Lt. (jg) Tomio Tsuji PO1. Daiseiki Tsubokura	Torpedoed Alchiba and sunk by PC-477 and SBD-3 dive bomber of VMSB-142	IBS45
	Sunk in 700 meters in IBS. Undiscovered. Located approx. half way between Savo and Lunga Point.
Kohyoteki 22 (I-16)	13 December 1942	Lt. (jg) Yoshimi Kado PO2. Toshio Yahagi	Claimed attacked a DD; successfully abandoned near Kamimbo	GUAD45
	Known site. Poor condition. Archaehistoria.org rediscovered and surveyed in 1994.

Discussion
The Kohyoteki were developed and designed to be launched from ramps at the stern of large ships. The original battle concept was these ships would steam in advance of the main imperial fleet and release the midgets into the path of the oncoming enemy units. As military technology rapidly advanced just prior to WWII, air power rose to prominence and made the surface vessel midget carriers too vulnerable to air attack so another deployment method had to be developed. This was successfully done using large fleet submarines carrying the Kohyoteki on the stern deck. The Kohyoteki crew could enter their mount from the mother submarine whilst still underwater through an ingenious water-tight connection hatch. In this way, the midget could be transported secretly close to the target and released. During WWII, this method was used to deliver Kohyoteki for attacks and worked well.

It appears, however, that this launching system may have had some disadvantages too and may have been the cause for the aborted Kohyoteki 30 mission. Most importantly, the release phase would have to be very carefully controlled. The lightly built, vulnerable control surfaces and other vital installations on the exterior of the 46 ton Kohyoteki could easily be damaged if physical contact was made with the 2500 ton mother submarine.  If the seas were even slightly rough, there would be a high risk of collision. Is this what occurred to Ha-30 on November 11, 1942? Were the seas rough that night? Did the stern of the midget collide with part of the mother submarine and damage the midget’s rudders?  The carrying of the Kohyoteki underwater also makes it vulnerable- it is somewhat exposed on the stern deck of a submerged submarine. Did something impact the rudders and damage them during transport? Were the rudders fluttering in the wake turbulence and this damaged them? An archaeological survey could provide the answers to these historical questions.

With the rudders inoperative, the midget would steam in circles. It would be uncontrollable. This could explain why they would not execute their first inclination which would be to steam towards the reception centre and abandon the damaged Kohyoteki there. Were they able to make way at all and possibly steam in a big circle ending up close to Savo’s shores where they abandoned the Kohyoteki there? Why say “sunk off Savo” and not “off Guadalcanal”?

Archaehistoria’s first attempt to locate the archaeological site of Ko-hyoteki 30
In January 1999, Archaehistoria conducted an expedition to Iron Bottom Sound to survey and explore for WWII archaeological sites. One of the objectives for the expedition was Kohyoteki 30. There was a possibility the crew had abandoned Ha-30 close to Savo’s shores or beached it on the coast. Could it be within range of SCUBA?.

The search for Ha-30 was combined with the main objective of the Archaehistoria January 1999 expedition – the locating of the heavy cruiser USS Astoria (CA-34) (See Site SAVO7) or possibly USS Vincennes (CA-44).

Two days were spent exploring the marine topography of Savo and extensively echo-sounding surveying Savo’s Eastern side and Northern end. All the field investigations for Ha-30 occurred on the first Savo-survey day: Thursday January 7, 1999.

Two boats were organised for the echo-sounder survey on January 7. A fibreglass canoe manned by Franck Bouley and Paul Martin of Solomon Sea Divers, with Kevin Denlay, took the outer deeper survey line. Richard Theakston and myself were in Ian Gardiner’s boat and conducted the shallower survey route. I recorded the conditions in my expedition diary:

Sea was glassy smooth – quite incredible and ideal. Took only one hour to reach Savo [from Point Cruz].

To find out about a possible local submarine wreck and other WWII wreckage, I landed on the island a number of times and enquired with the Savo Islanders.  My expedition diary records how the day panned out and the typical miss-information combined with isolated truths, despite my fluent pijin language skills, and good Melanesian cultural knowledge:

…we searched 55-60 meters and the bottom was rather convoluted at this depth. Some “fingers” extended seaward some distance but dropped off steeply too. Came across a friendly [Melanesian] guy fishing in a canoe opposite Tasimania. The guy was very helpful and suggested a small submarine wreck! [this was unprompted by me]. That had to be Ko-hyoteki 30!! He also said only one plane crashed on the island – must only be VS-64 [sic] SOC-1. He was oppo Tasimania & said the sub was to the North! He said it was near Simbo and to ask the people there. We met Paul’s boat which was behind some miles because they had to go real slow to maintain picture quality. [On the echo sounder screen].

 

Figure 3
A lone fisherman in traditional wooden canoe off Savo in the evening of November 2, 2011. On the first attempt to locate Kohyoteki 30 we pulled alongside a fisherman like this off Tasimania on the West coast, who provided us information on WWII sites on Savo. Mountains of Cape Esperance on Guadalcanal in the distance. [Photo by Ewan M. Stevenson].

Kevin [with Franck Bouley and Paul Martin] had searched around the 60-70m mark. [no bottom feature like a heavy cruiser had been seen] We decided to go and dive the sub. We pulled in where we saw smoke [smoke from garden or cooking fires indicates habitation] coming and where we thought Simbo was but we were just South of it at a “resort”, it was rather pleasant and called “Leqalau”. The native owner “Alan ”ⁱ was proud [of his resort]…he sent a boy with us, Tuomei, to ask at another village if we could dive the sub. We headed South. Finally, it turned out we had to ask at Kalaka. Very steep hills immediately behind shore. Kalaka was miles & miles South & East from where the fisherman said the sub was off Simbo. We got feelings of wild goose chase but eventually picked up a native “diver” (spearfisherman) from Kalaka who indicated the El Torito (Walter Starck’s expedition) found a “sub” off this rock near Kalaka.

 I was well aware of Dr. Walter “Walt” Starck’s expedition in the early 1970’s to the Solomons. (My father, Charles C. “Jock” Stevenson, had SCUBA dived with some of the members). I also knew they carried a small 1500 lb yellow “wet” submarine on their research vessel, the El Torito.

Figure 4
Dr. Walter “Walt” Starck’s research vessel El Torito moored against the cliffs at the Southern entrance to Sandfly Passage in the Florida Islands adjacent Savo Island in the early 1970’s. Note the yellow submarine on deck. This was used for dives off Savo and may have been the source of confusion in my January 1999 enquiries with the local Savo islanders. [Photo by Walter Starck, as published facing p.113 Sharks and Other Ancestors by Doak].

There is no written record/history in Melanesian culture, so history is recorded by repeated verbal renditions of events. Obviously such verbal folklore is inherently prone to interjecting errors over time which warps the verbal history record. It was quite likely the “sub” was not “found” by Walt’s expedition but was rather simply just the yellow one “used” by them. Indeed, I later confirmed the El Torito expedition did conduct submarine dives off Savo. There are few places on Savo which has significant coral reef. Most of the coastline is too exposed, and the numerous streams suppress coral growth. Kalaka is the only place with large reef areas. I was sceptical of the Savo Islander’s report that the El Torito expedition had found a submarine off Kalaka, but with a beautiful coral reef visible under the boat, why not have a nice dive looking for it? Kevin Denlay, Richard Theakston, Franck Bouley and I geared up and dropped into the beautifully clear water. The reef extended out from the South West coast of Savo near Kalaka in a South West direction. Our visual search covered the South East side, off the edge of the reef on the sand. The dive was mostly conducted at 25-30m, with maximum depth of 33m. I stayed well above the bottom, visually searching down the sand slope to an estimated 45m or more due to the good visibility. I recorded the dive in my diary as follows:

Everyone dived looking for the midget. As soon as at depth 30m or so I saw a shark but noticed Rich not looking so swam down and got his attention real quick lest he missed the shark. The shark stayed so it was great to see it. I pressed ahead and didn’t pay too much attention to it. Ian & Paul and Tuomei stayed in boats. Ian was in boat awaiting us divers. I stayed as deep as long as possible but off the bottom at edge of viz range – [visually] cover far more ground. Saw small tuna, kingfish, big GT, had two sharks around for awhile. Great dive. No one found any sub. The native diver remembered them saying they found a sub! The El Torito visited the area in early 1970’s or perhaps 1975? Amazing they cld recall it.

I later contacted Dr. Walter Starck in Australia who confirmed they never found any submarine wreck on Savo.  The book Sharks and Other Ancestors: Patterns of Survival in the South Seas which was written on the expedition by Wade Doak, writes about the diving at Savo, but makes no mention of any wreckage found.

Regarding the sharks of Savo, it is common knowledge they are particularly prevalent there, collaborated by this passage from an article published in 1964 by long serving pre-war BSIPⁱⁱ resident, R.J.A.W. Lever:

Sharks have always been very savage in the waters off Savo, it is thought because of the former custom of certain tribes of placing their dead in the water instead of burying them. The writer, from the safety of a government schooner, saw several active grey-nurse sharks estimated to be at least 20 feet long.

The confined coral reef areas on Savo at Kalaka naturally attract the most SCUBA diving and local spear fishing. The reefs are crucially important to the Savo Islanders for sustenance. Much underwater attention is focused on the area. The first SCUBA dives on the Kalaka Reefs were in the early 1970’s. Savo has continued to be SCUBA dived occasionally through the 1970’s until today. As the Kalaka Reefs are in the shelter of the South East trades winds, this is an added attraction. This underwater area would be the most dived and most explored of Savo’s underwater terrain. The Melanesian spear fishermen are highly skilled and regularly descend 20 meters or more to spear fish. They also spear fish almost every day to feed their families. On very clear underwater visibility days they would be able to visualize 40-50 meter deep sea floor. A protruding conning tower of a small submarine would be noticed. Considering the attention of European SCUBA divers in the area, it seems highly likely if such a site existed it would be well known today.

Savo Island reefs, like many in the third world areas today, are becoming over- exploited as food resources by local populace. Fish form a crucial part of the protein dietary intake of islanders. Access to modern medicine and better understanding of hygiene, has meant a rapidly burgeoning island population. A google earth view of Savo easily shows the population density and intensive land cultivation. All this comes at the price of the natural environment. There is only a limited area of coral reef with fish, and a limited area of land suitable for gardening. At some point, the island will run out of land for gardens and all the fish have been eaten. There are no marine or land reserves on Savo. Every square foot is exploited by islanders to survive. The issues facing Savo, we all know, are not peculiar to the island, but how can they be peacefully solved? It certainly is sad to see increasingly less habitat for the famous Savo megapode bird and coral reefs devoid of fish.

After our pleasant dive at Savo, Franck’s boat and passengers returned direct to Honiara. We motored back up the West side of Savo to return Tuomei to his home at Leqalau. On the return to Honiara across Iron Bottom Sound, my diary records the following:

Sea glassy. No wind. We speed back to HIRⁱⁱⁱ , and saw a manta ray flip and a pod of pilot whales on the surface. We slowly motored up to them & got incredibly close before they dived.

HMNZS Resolution (A14) of the Royal New Zealand Navy underwater surveys Savo Island November 2011
The New Zealand Navy’s hydrographic ship conducted a tour of the Solomons in October – November 2011 under the command of Lt. Cdr. Matt Wray. The ship’s work comprised hydrographic surveys, goodwill visits, EOD work and fisheries patrols. I was assigned to the ship in Iron Bottom Sound as historical advisor regarding identifying WWII sites found, assisting in directing sonar surveys and providing pin-point accuracy for known wrecks to be surveyed in detail. In addition, certain historical targets were proposed for locating. It was an opportunity to put a lifetime’s worth of research into WWII archaeology of the Iron Bottom Sound area to good use.

 

Figure 5
Southern end of Savo Island off the port bow of the HMNZS Resolution (A14) as the hydrographic ship approaches to begin the most detailed underwater sonar survey to date of Savo Island. Although Ha-30 was not the primary objective, there was every possibility it might have been discovered during the ship’s survey. [Photo by Ewan M. Stevenson].

 

The mission was officially christened Operation Calypso. It was a very successful expedition, with some sixty WWII and other wrecks surveyed and many new ones discovered. A large part of the success was due to the tenacity and outstanding exploratory character of the ship’s commander. The Savo area was included in survey plans. The primary targets were the Royal New Zealand Air Force C-47A Dakota NZ3521 (Site SAVO3) ditched off the Northern end of Savo and the USS Astoria (CA-34) (Site SAVO7). This necessitated focusing on the Eastern and Northern sides of Savo which the ship surveyed in detail using Reson MBES^iv sonar down to 300 meters on the afternoon of November 2 and during the night of November 4.

Lt. Cdr. Matt Wray also later in the month, continued sonar searching Savo and conducted a brief sonar sweep off the West side of the island. Disappointingly, no WWII wreckage of any kind was identified in the sonar surveys off Savo Island.

Future Archaeology
Whether there is any basis for Kohyoteki 30 being sunk close offshore Kalaka is unknown. It might be worth a detailed side scan sonar or magnetometer survey in the area. Like all of Savo’s underwater topography, it drops off very quickly into exceedingly deep water. It would not take long to verify if any target was within range of SCUBA in the area.

Archaehistoria has a special interest in Kohyoteki and has researched a number of their archaeological sites. In all known cases, the 80-foot long submarines sink and come to rest upright on the bottom. This is due the inherent stability designed into the submarine. This means the submarine sail will be upright and present an excellent target for side scan sonar. From the top of the sail (encompassing access hatch) to the keel is 3.10 meters.

The pair of 18-inch Type 97 torpedoes will still be loaded, unfired. It is Archaehistoria’s recommendation that these torpedoes are defused and de-powdered and thereby rendered safe using modern EOD techniques rather than the usual brutal destruction by demolition explosive charges and consequent severe damage to a historic artefact. The technology is available to render safe and preserve these torpedoes as historic items. These torpedoes operated on the advanced kerosene/oxygen fuel mixture. Very few Type 97 torpedoes exist in museums^v.

The Kohyoteki were all welded and made from 8mm cold rolled steel plates. In archaeology it is a general knowledge that saltwater submerged steel plate corrodes at a rate of roughly 0.1mm per year. This means the 8mm plating has an approximate life of 80 years. We are rapidly approaching this vintage.

How did the Ha-30 crew scuttle their mount? Did they activate a demolition charge installed like the ones used in the Hawaiian operation? Did they open valves and flooded the midget? The Kohyoteki crew could trim the submarine by using ballast tanks and it is probable they could intentionally upset the trim on the surface and sending the midget to the seafloor as they scrambled out the access hatch. Did they close the hatch behind them? An archaeological survey might find the answers to these questions.

One interesting aspect of an archaeological survey of this site might be confirming the rudder damage. How bad was the damage? Might the damage indicate what caused it? This aspect could also assist in confirming identification of the Kohyoteki as Ha-30.

If the results of a more focused instrument survey off Kalaka are negative, the subsequent search area for Ha-30 is very large and very deep. The Ha-30 was released approximately between Cape Esperance/Kamimbo Bay at the Western end of Guadalcanal and Savo Island. If Kohyoteki 30 was scuttled close to its initial launch site in this area, the search depths are 900-1200 meters. If this is the case, it is likely it will be a long time before the archaeological site of Kohyoteki 30 is discovered. In the meantime, electrolysis and galvanic corrosion will continue to deteriorate the condition of this historic artefact.

Significance

• One of eight Kohyoteki expended during the Guadalcanal Campaign
• One of seven Kohyoteki archaeological sites in the Iron Bottom Sound area
• One of 52 Kohyoteki Type A built at Ourazaki, Kure. (one Type B and 36 Type C were built).
• Ha-30 was one of 23 Kohyoteki ordered in December 1940.
• Intact, whole, untouched site

Acknowlegments

• The people of Savo Island, who are responsible for the management of the Savo Island WWII archaeological sites
• Members of the Archaehistoria January 1999 Expedition to Iron Bottom Sound: Richard Theakston, Franck Bouley, Kevin Denlay, Ian Gardiner, Paul Martin.
• Special thanks to Kevin Denlay for so generously supporting the January 1999 Archaehistoria Expedition.
• Sgt. Gene Leslie, USMC (Ret.) for continuously supporting Archaehistoria with research materials from the USA.
• Peter Flahavin for enthusiasm and continuous research support, particularly with photographic research.
• R. Adm. Kazuo Ueda, JSDMF, (Ret.), President of the Japanese Midget Submarine Association
• The commanding officer, Lt. Cdr. Matt Wray, and crew of the HMNZS Resolution (A14) during Operation Calypso, November 2011 Expedition to Iron Bottom Sound.
• Cdr. Phil Bradshaw, RNZN
• The Kiwi Odyssey Team: Cdr. Michael Stephens, RNZNR, Glen and Evan Christie
• Sir Allan Kemakeza, former Prime Minister for the Solomon Islands. Thank you for your helpful assistance in January 1999. Currently serving as Speaker of the National Parliament of the Solomon Islands.
• The lone unknown fisherman off Tasimania.

References
Cutler, Andrew.
Op Calypso. Navy Today Issue 164 (December 2011): pp. 28-29.

Wade, Doak
Sharks and Other Ancestors: Patterns of Survival in the South Seas. Auckland: Hodder and Stoughton, 1975, 333pp.

Doak, Wade. (El Torito expedition)
Email correspondence April 2013

Itani, Jiro and Lengerer, Hans and Rehm-Takahara, Tomoko.
Japanese Midget Submarines: Kohyoteki Types A to C.  in Warship 1993, Robert Gardiner, editor, pp. 113-129. London: Conway Maritime Press Ltd, 1993.

Gakken Vol. 35.
This is a most detailed Japanese volume on Kohyoteki.

Kazuo, Ueda, R.Adm., JMSDF. (President of now–defunct Midget Submarine Association)
1994-2000. Correspondence, publications, notes, tables on Ko-hyoteki operations during WWII.

Kemp, Paul.
Midget Submarines of the Second World War. London: Chatham Pub., 1999, 125pp.  

Lever, R.J.A.W.
Savo, British Solomon Islands Protectorate. South Pacific Bulletin Vol. 14, No. 3 (July 1964): pp. 41-42.

Polmar, Norman and Carpenter, Dorr B.
Submarines of the Imperial Japanese Navy 1904-1945. London: Conway Maritime Press Ltd, 1986, 176pp.

Starck, Walter. (El Torito expedition)
Email correspondence c. 2000.

Stevenson, Ewan M.
The Archaehistoria Bibliography of the Guadalcanal and Solomon Islands WWII Campaigns. Manuscript only. Auckland: Archaehistoria Publishing, 11 January 2010, 491pp.

Stevenson, Ewan M.
Notes, expedition diary, sketches, sound recordings, video, still images. For January 1999 Archaehistoria Expedition.

Stevenson, Ewan M.
Notes, expedition diary, sketches, sound recordings, video, still images. For November 2011 Archaehistoria Expedition aboard HMNZS Resolution (A14).

Stevenson, Ewan M.
SAVO. Black plastic folder. 18 September 2011. Brief sheets, survey plans and other materials relating to Savo prepared for expedition aboard HMNZS Resolution.

Wray, Matt Lt Cdr. , RNZN
Email correspondence, reports, conversations,  August 2011 – 2013.

____________________________