Utsuro-bune, also Utsuro-fune and Urobune, refers to an unknown object which allegedly washed ashore in 1803 in Hitachi province on the eastern coast of Japan. Accounts of the tale appear in three texts: Toen shosetsu (1825), Hyoryu kishu (1835) and Ume-no-chiri (1844).
According to legend, an attractive young woman arrived on a local beach aboard the "hollow ship". Fishermen brought her inland to investigate further, but the woman was unable to communicate in Japanese. The fishermen then returned her and her vessel to the sea, where it drifted away.
Historians, ethnologists and physicists such as Kazuo Tanaka and Yanagita Kunio have evaluated the "legend of the hollow boat" as part of a long-standing tradition within Japanese folklore. Alternately, certain ufologists have claimed that the story represents evidence for a close encounter of the third kind.