Kublai Khan's lost fleet

In 1274 AD storms had wrecked a Mongol invasion fleet trying to attack Japan, killing more than 20,000 troops. In 1281 the Mongol emperor tried again with a vast fleet of 4400 ships and maybe more than 100,000 Chinese and Mongol soldiers. These numbers are based on contemporary sources and have not been confirmed. During the invasion attempt, Japanese naval attacks and a another subsequent typhoon sank most of the ships off the Japanese coast, killing most of the soldiers.
These two storms that saved Japan added a new phrase in the Japanese language, "kami kaze", meaning "divine wind". These two events have been claimed to be the largest sea disasters in history. At any rate, it definitely halted the Mongol expansion east, that started with Gengis Khan's conquest of China in the early 13th century.
Centuries later, several artefacts have been recovered from the seabottom of the Imari Gulf. Major remains were found in 1981 by Professor Torao Mozai. Much more is likely to be buried below the bottom sand. Local fishermed have brought up artefacts including the personal seal of a Mongol commander, inscribed in both Chinese and the Phagspa script used to write the Mongolian language. Among other finds are iron swords, stone catapult balls, spearheads and stone anchors.
Since 1991, investigations are led by archaeologist Kenzo Hayashida of the Kyushu Okinawa Society for Underwater Archaeology (KOSUWA). After 10 years of search, they made a major find in October 2001 – an entire shipwreck, that appears to originate from Fujian in south China. The scattered remails of the Mongol Navy ship were located on 15 m depth, below ca 1 m of mud on the seabottom. The ship appears to have been ca 70 m long. Among the finds are several ceramic projectile bombs, filled with gunpowder and iron shrapnel.