Invented in 1591 by Li Soon Sin, the Turtle ship, also known as Geobukseon or Kobukson, was a type of large warship belonging to the Panokseon class in Korea that was used intermittently by the Royal Korean Navy during the Joseon Dynasty from the early 15th century up until the 19th century | Ripley's Believe It or Not!
Image 2: The Turtle Ships of Medieval Korea. While the Japanese had firearms, Korean technology had developed far past Japan’s due to their contact with China. The key to the turtle ship’s power were its heavy cannon, about a dozen mounted on each side. The Japanese, who never mounted guns on a boat or ship, preferred to get in close and board the ship, fighting in hand to hand combat.