By the 3rd century BC, the Chinese were building oceangoing merchant vessels up to 80 feet long and weighing up to 60 tons. According to the Shih Chi chronicle, in 219 BC, during the reign of Emperor Shih Huang, a fleet of ships, led by Captain Tzu Fu, left China for Fu Sang, a far-off land to the east, also known as the Isle of the Immortals. The purpose was to bring back the legendary ling chih mushrooms for the ailing emperor. (source davidpratt.info May 2009)