1513: Juan Ponce de León names them Los Mártires ("The Martyrs") after crew deaths in a Calusa attack.
Early Spanish charts: Cayo Hueso ("Bone Key") for Key West (alleged bone pile); Cayos de las Tortugas ("Turtle Keys").
1700s: English pirates, wreckers, and sailors adopt "The Florida Keys"—from Spanish cayo (small island).
1822: US takes possession; "Key West" formalized from Cayo Hueso.
The name reflects Spanish exploration, English maritime use, and the islands' coral cay nature.