A group of six divers led by The Dive Shop Cambodia owner Dennis Funke have discovered what they believe is the wreckage of a Japanese merchant vessel sunk by a US Navy submarine during World War II.

The cargo ship is suspected to be the steam-powered Burma Maru, and was discovered on Tuesday last week over the course of a two-day dive. The find was the result of nearly five years of research, Funke told The Post yesterday.

“I got the information from the log books of the submarine that shot the boat,” he said, adding that the shipwreck was within 1 nautical mile of the coordinates logged by the Navy submarine, the USS Swordfish.

Funke – whose team of divers based in Cambodia and Thailand included Tim Lawrence, Ivan Karadzic, Oliver Zaiser, Mikko Paasi and Leon Webber – said that the wreck, which was about 60 nautical miles (more than 110 kilometres) from Koh Rong island, presented a daunting technical challenge. Diving at a depth of 52 to 67 metres, the team made use of techniques and military-grade technology they say had not been put to the test before in the Kingdom.

“I never expected to make such a deep dive in Cambodia,” he said.

According to their observation, the wreck is 120 metres long, and while name markings were not visible, it matched the expectations they had for the Burma Maru, which was sunk on June 12, 1942.

“What we believed is that the ship was hit by a torpedo [that] ripped off the bow of the boat, and so it began sinking head first, which put pressure on the stern of the wreck, which blew out the doors and windows, throwing out debris,” he said.

According to records by Lloyd’s Register of Shipping, the Burma Maru was built in 1917 at the Kawasaki Dockyards in Kobe, Japan, measured 117 metres in length and its last owner was the Nanyo Kaiun KK shipping company. The ship’s cargo at the time of the sinking has yet to be determined.

The sinking of the Burma Maru – which was not a Japanese Imperial Navy vessel – fell under the December 7, 1941, order by the US chief of naval operations to conduct unrestricted submarine warfare against Japan.

The Swordfish, for its part, is notable for being the first US submarine to sink a Japanese ship in the Pacific Theatre. Although it would eventually go missing on January 12, 1945, off the coast of Japan – it sank a total of 12 Japanese vessels during the war.

The Gulf of Thailand is considered by many divers as one of the last untapped troves of shipwrecks, particularly from the World War II era.

“It’s a big unknown. We believe there must be plenty more shipwrecks in Cambodian waters,” Funke said.

While Funke’s team mostly observed the outside of the ship due to safety concerns, he said the find was the highlight of his diving career. “It’s not many divers that get to find a ship at all.”

As for the future of the wreckage, Funke said it could become a dive site for advanced divers.

“It’s pretty hardcore,” he said. Although its fate in part depends on whether it is located within Cambodian or international waters, Funke added that he hopes it does not get scavenged for scrap metal.

“From a moral perspective . . . it’s basically a grave and people should rest in peace.”

Watch The Dive Shop Cambodia's footage from the expedition: