On December 7, 1941, the world changed forever when a surprise aerial assault struck Pearl Harbor. However, a lesser-known chapter of that infamous day unfolded beneath the waves. While the skies rained fire, the Imperial Japanese Navy deployed five top-secret, two-man Type A midget submarines to infiltrate the harbor.
For nearly two decades, the fate of one of these vessels remained a complete mystery—until construction workers unexpectedly struck steel in the waters off Oahu in July 1960.
The Unplanned Burial at Keehi Lagoon
The submarine, officially launched by the large “mother” submarine I-18 in the early morning hours of December 7, was meant to slip past American defenses and torpedo battleships inside the harbor.
However, things did not go according to plan. Due to navigational difficulties or mechanical failures, the sub never made it inside. Unbeknownst to the U.S. military, the two-man Japanese crew abandoned the vessel in Keehi Lagoon near the entrance to Pearl Harbor, leaving it fully loaded. Although they set a scuttling charge designed to destroy the evidence, the explosives failed to detonate. The sub slowly sank into the mud, where it stayed undisturbed for 19 years.
The 1960 Recovery (Catalog # KN-2589)
In July 1960, the submarine was rediscovered during dredging operations to expand the Honolulu International Airport. Photographed immediately after its recovery, the rusted hull became a historic sensation.
Navy divers and historians made several fascinating discoveries upon inspecting the vessel:
| Feature | Details & Findings |
|---|---|
| Torpedo Tubes | Both tubes still contained live, un-fired torpedoes, proving the sub never engaged in combat. |
| The Hull | Remarkably intact despite spending nearly two decades underwater. |
| Crew Status | No human remains were found inside, confirming the crew successfully abandoned the vessel. |
Where Is the Submarine Today?
Following its recovery, the United States Navy carefully removed the live torpedoes. In a gesture of goodwill, the U.S. government returned the historic artifact to Japan in 1962.
Today, the meticulously restored I-18 midget submarine stands on display at the former Imperial Japanese Naval Academy at Eta Jima (now the JMSDF Command and Staff College), serving as a powerful, silent monument to the chaotic opening hours of the Pacific War.