1900s
- 1900 – Three lighthouse keepers working on the Flannan Isles (off the northwestern coast of Scotland) disappeared in a mystery commemorated in the ballad Flannan Isle and the opera The Lighthouse.
- 1909 – Joshua Slocum (65), Canadian-American sailor and first man to sail single-handedly around the world (1895–1898), disappeared after setting sail from Vineyard Haven on Martha's Vineyard alone, bound for South America, aboard the same 36 ft 9 in (11.20 m) sloop Spray he had used for his circumnavigation.
Read more about this topic: List Of People Who Disappeared Mysteriously