Joshua Slocum (February 20, 1844 – on or shortly after November 14, 1909) was the first person to sail single-handedly around the world. He was a Nova Scotian-born, naturalised American seaman and adventurer, and a noted writer. In 1900 he wrote a book about his journey, Sailing Alone Around the World, which became an international best-seller. He disappeared in November 1909 while aboard his boat, the Spray.

Joshua Slocum was born on February 20, 1844, in Mount Hanley, Annapolis County, Nova Scotia (officially recorded as Wilmot Station), a community on the North Mountain within sight of the Bay of Fundy. The fifth of eleven children of John Slocomb and Sarah Jane Slocombe née Southern, Joshua descended, on his father's side, from a Quaker known as "John the Exile", who left the United States shortly after 1780 because of his opposition to the American War for Independence. As part of the Loyalist migration to Nova Scotia, the Slocombes were granted 500 acres (2.0 km²) of farmland in Nova Scotia's Annapolis County.

Joshua Slocum was born in the family's farmhouse in Mount Hanley and learned to read and write at the nearby Mount Hanley School. His earliest ventures on the water were made on coastal schooners operating out of the small ports such as Port George and Cottage Cove near Mount Hanley along the Bay of Fundy.

When Joshua was eight years old, the Slocomb family (Joshua changed the spelling of his last name later in his life) moved from Mount Hanley to Brier Island in Digby County, at the mouth of the Bay of Fundy. Slocum's maternal grandfather was the keeper of the lighthouse at Southwest Point there. His father, a stern man and strict disciplinarian, took up making leather boots for the local fishermen, and Joshua helped in the shop. However, the boy found the scent of salt air much more alluring than the smell of shoe leather. He yearned for a life of adventure at sea, away from his demanding father and his increasingly chaotic life at home among so many brothers and sisters.

He made several attempts to run away from home, finally succeeding, at age fourteen, by hiring on as a cabin boy and cook on a fishing schooner, but he soon returned home. In 1860, after the birth of the eleventh Slocombe child and the subsequent death of his kindly mother, Joshua, then sixteen, left home for good. He and a friend signed on at Halifax as ordinary seamen on a merchant ship bound for Dublin, Ireland.

From Dublin, he crossed to Liverpool to become an ordinary seaman on the British merchant ship Tangier (also recorded as Tanjore), bound for China. During two years as a seaman he rounded Cape Horn twice, landed at Batavia (now Jakarta) in the Dutch East Indies, and visited the Maluku Islands, Manila, Hong Kong, Saigon, Singapore, and San Francisco. While at sea, he studied for the Board of Trade examination, and, at the age of eighteen, he received his certificate as a fully qualified Second Mate. Slocum quickly rose through the ranks to become a Chief Mate on British ships transporting coal and grain between the British Isles and San Francisco.

In 1865, he settled in San Francisco, became an American citizen, and, after a period spent salmon fishing and fur trading in the Oregon Territory of the northwest, he returned to the sea to pilot a schooner in the coastal trade between San Francisco and Seattle. His first blue-water command, in 1869, was the barque Washington, which he took across the Pacific, from San Francisco to Australia, and home via Alaska.

He sailed for thirteen years out of the port of San Francisco, transporting mixed cargo to China, Australia, the Spice Islands, and Japan. Between 1869 and 1889 he was the master of eight vessels, the first four of which (the Washington, the Constitution, the Benjamin Aymar and the Amethyst) he commanded in the employ of others. Later, there would be four others that he himself owned, in whole or in part.