Watch Unsinkable: Japan's Lost Battleship (2020) HD Full Movie Free on SolarMovie. Watch Unsinkable: Japan's Lost Battleship (2020) online free. October 24, 1944, Japan's navy gambles on a decisive victory against the United States to turn the t...October 24, 1944, Japan's navy gambles on a decisive victory against the United States to turn the tide of World War II. Instead, Musashi, its top-secret super battleship, ends up at the bottom of the ocean.