Marine researchers have found a pair of Imperial Japanese Navy submarines on the sea floor off Hawaii's Oahu Island – vessels so advanced for their day they would provide plenty of fodder for a fresh novel by Tom Clancy.

Known by their vessel numbers, the I-14 was a 375-foot submarine aircraft carrier – its crew capable of assembling and launching two float-plane bombers in roughly 20 minutes. The other craft, the I-201, was an attack submarine, twice as fast as any in the US fleet and faster than subs in any other Navy during World War II.

"This is one of the most significant marine-heritage findings in recent years," according to Hans Van Tilburg, a marine archaeologist who is the maritime-heritage coordinator for the National Oceanic and Atmospheric Administration's National Marine Sanctuaries in the Pacific. The find was announced Thursday.

"These submarines are 60-year-old time capsules offering first-hand insight into a military technology that was far ahead of its time," he says. The subs were so advanced, Mr. Van Tilburg continues, that had they appeared earlier in the war and in larger numbers, "the submarines had the potential to turn the tide of war."

Among the approaches Japanese designers used: a rubbery coating on the outside of the hull and conning tower to absorb radar and reduce the likelihood that sonar aboard US destroyers or subs would pick up sounds from inside the Japanese vessels.

The aircraft-bearing subs were designed to bring the war to the US mainland and strategic choke points such as the Panama Canal by hiding offshore and releasing the single-engine bombers on what would be one-way missions. The tactic Japanese war planners envisioned provided a chilling foretaste of tactics the US and Russian navies would use with their ballistic-missile submarines during and after the cold war.

Indeed, the I-14's larger sibling, the I-400 class subs, could be considered the forerunners of today's ballistic-missile "boomers."

At 400 feet long, the I-400 subs were designed to travel 37,500 miles without refueling – enough range to cruise around the world 1-1/2 times between fill-ups and have enough fuel left for their three aircraft. Intended targets for the subs' bombers included Washington and New York. None of these long-range missions were carried out.

The expedition was conducted using manned submersibles operated by the Hawaii Undersea Research Laboratory, a cooperative venture between NOAA and the University of Hawaii. Partial funding for the effort came from the National Geographic Society's cable TV arm, the National Geographic Channel.

Today's announcement comes four and a half years after the same submersible team spotted the remains of one of the largest subs, the I-401 off the Hawaiian Islands.

The I-401, along with the I-14 and I-201, were captured at war's end and sailed to Hawaii, where US naval intelligence officers could plumb the ships' secrets. They are three of five advanced Japanese subs the US sailed to Pearl Harbor after the war. All were scuttled to avoid having to share the information with the Pacific war's late-comer and co-claimant to such prizes, the former Soviet Union.

For a US submarine officer of the day, the largest of these Japanese vessels were little short of awe inspiring.

"The giant submarine's proliferation of compartments was hard to get used to," wrote the late Thomas Paine, who at the time was a lieutenant in the US submarine service and was an officer on the I-400's prize crew as it sailed from occupied Japan to Pearl Harbor.

Along the way, the crew tweaked the galley to fit American taste buds and added other amenities.

Thus, Mr. Paine writes, his tale "may be historically significant when future underwater archaeologists diving on the I-400 in deep water off Hawaii wonder why her scuttlebutts [water fountains] were equipped with General Electric refrigerated fountains."

"Why did her galley feature gourmet cooking equipment (including an ice cream machine)?" he writes. "Why deluxe porcelain plumbing fixtures in the heads? Why crude military electronics topside, while bunks below were wired for music from a deluxe jukebox with flashing colored lights? You have the explanation."

Indeed, within the next week, the submersible team that discovered the I-401, I-14, and I-201 will be taking their craft for test dives ahead of a new undersea research season. The team plans to use those dives to look for the I-400, as well as the I-201's sister ship, the I-203.

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