- Squire Trelawney may have been named for Edward Trelawney, Governor of Jamaica 1738–52.
- Dr. Livesey may have been named for Joseph Livesey (1794–1884), a famous 19th-century temperance advocate, founder of the tee-total "Preston Pledge". In the novel, Dr. Livesey warns the drunkard Billy Bones that "the name of rum for you is death."
Various claims have been made that one island or another inspired Treasure Island:
- Norman Island in the British Virgin Islands, supposedly mentioned to a young Stevenson by a sailor uncle, and also possessed of a "Spyglass Hill" in the same way the fictional Treasure Island was.
- Dead Chest Island, a barren rock in the British Virgin Islands, which Stevenson found mentioned in Charles Kingsley's At Last: A Christmas in the West Indies; and which he said "was the seed" for the phrase "Dead Man's Chest".
- Small pond in Queen Street Gardens in Edinburgh, said to have been visible from Stevenson's bedroom window in Heriot Row.
- The Napa Valley, California, where Stevenson spent his honeymoon in 1880, as narrated in his The Silverado Squatters (1883).
- Osborn (now Nienstedt) Island, an island in the Manasquan River in Brielle, New Jersey. Stevenson supposedly visited the island in May 1888 (five years after writing Treasure Island) and christened it "Treasure Island"
- Fidra in the Firth of Forth, visible from North Berwick where Stevenson had spent many childhood holidays.
- Unst, one of the Shetland Islands, to which the map of Treasure Island bears a very vague resemblance.
- La Isla De La Juventud in Cuba is also associated by some with the book, and is supposed to have similarities with the map drawn by Stevenson, as well as historical connections with pirates. The island in the book is described as having pine trees running down to the shore and the Cuban island used to be called La Isla de Pinos, the Island of Pines.
- In The Adventures of Ben Gunn, Gunn gives its real name as Kidd's Island, and identifies it as an outlying island of the Leeward and Windward Islands, south-south-west of Tobago (p. 119-120).
- The Llandoger Trow in Bristol is claimed to be the inspiration for the Admiral Benbow, though the inn in the book is not supposed to be in Bristol.
- An inn named Admiral Benbow in Penzance, Cornwall.
- The Hole in the Wall, Bristol is claimed to be the Spyglass Tavern.
Flint's death house
The Pirate's House in Savannah, Georgia is where Captain Flint is claimed to have spent his last days, and his ghost is claimed to haunt the property.