With more time, military experts say, a fleet of revolutionary Japanese super-submarines could have changed the course of World War II.
Some were designed to launch bombers on kamikaze missions against New York City, Washington, D.C., and the Panama Canal. Others were thought to be twice as fast any other submarine used in the war.
None had the chance to execute their stealth missions against the U.S. mainland or critical targets in the Pacific during the war.
But after the war ended and the U.S. Navy seized and surveyed the vessels, it made a drastic decision: Each submarine was taken off the coast of Hawaii in 1946 and shot down to the ocean floor to keep the technology from falling into Soviet hands.
For years since, divers have scanned the depths of the Pacific to recover the subs and their technological secrets but to no avail.
A National Geographic Program premiering Tuesday documents a team of researchers' successful hunt for the super-submarines, which have not been seen by human eyes for more than 60 years.
"This is one of the more significant marine heritage findings in recent years," Dr. Hans Van Tilburg of the National Oceanic and Atmospheric Administration's Office of National Marine Sanctuaries said in a statement. "These submarines are 60-year-old time capsules offering firsthand insight into a military technology that was far ahead of its time, so much so that if introduced earlier and in greater numbers, the submarines had the potential to turn the tide of war."
In a news conference last week in advance of the television premiere of "The Hunt for Samurai Subs," National Geographic Channel, NOAA and the University of Hawaii announced that the researchers had recently discovered two of the fleets' five submarines.
"These submarines were highly advanced and had very prominent targets," said Mark Fowler, the program's executive producer.
The I-14, which housed and launched two aircraft, was designed to launch attack bombers off the East Coast to target major U.S. cities. The I-201 fast-attack sub was twice as fast as any other submarine at the time.
"And the Americans … had no idea that they existed," Fowler said. "These were the first time any military had ever pulled off an aircraft-carrying submarine to this level."
Since 1992, researchers with the Hawaii Undersea Research Laboratory have been diving off the coast of Hawaii to search for the high-tech submarines.
In March 2005, Terry Kerby, the laboratory's submersible operations director, and his team discovered the first of the fleet, an I-401 aircraft carrier capable of traveling one and a half times around the globe and launching three strategic bombers.
But although they continued to scan the ocean floor near the first submarine, they could not locate the remaining four.
It wasn't until a new piece of information emerged that the team started to approach success.