The Japanese submarine I-201 was a World War II

World War II

World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

, diesel-powered submarine. It was captured at the end of the war by American forces. After examination of its design, it was sunk off Oahu in 1946. It was discovered in 2009 by the Hawaii Undersea Research Laboratory

Hawaii Undersea Research Laboratory

The Hawaii Undersea Research Laboratory is a regional undersea research facility under the auspices of the U. S. government's National Oceanic and Atmospheric Administration National Undersea Research Program and administered by the University of Hawaii. Its headquarters are at University of...

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The submarine was one of the fastest diesel submarines launched. It had a rubber coating that was intended to make it less detectable by sonar or radar.

The submarine featured retractable bow planes and deck guns coupled with a sleek designed conning tower. These features enabled the sub to reach a top speed of just over 20 knots while submerged. She also was capable of being submerged for 30 days at a time before needing to resurface making her a formidable foe.