Noticed by Ferdinand Magellan in 1520, who gave nearby Cape San Antonio its name, Spanish authorities first surveyed the area in 1580. Led by reformist Governor Hernando Arias de Saavedra, his Guaraní staff christened the spot Rincón del Tuyú ("muddy corner"). First mapped by British Jesuit Thomas Falkner in 1744, the neighboring stream was named San Clemente by Spanish Jesuit José Cardiel.
The waterfront area was soon purchased by the Ortiz de Rozas family, one of Argentina's most well-established landowners. Sold to another prominent family, the Leloirs, in 1816, the area became a sheep ranch. A descandant of the Ortiz de Rozas', General Juan Manuel de Rosas, had the area incorporated into a district of the Province of Buenos Aires in 1825, the area's first assigned jurisdiction since national independence in 1816; as Governor, Rosas brutally repressed a local insurrection in 1839 against his repressive rule. Following Rosas' 1852 overthrow, the area was given a county seat (Mar del Tuyú) in 1864 and, with the arrival of abattoirs, the government had fishermen's docks, a canal between San Clemente and Buenos Aires, a railhead and two lighthouses built between 1878 and 1902.
Prospering during the 1920s, the Argentine middle class first became widely aware of the idyllic coast through the efforts of Mayor Jorge Gibson, who had the local coastline graded into public beaches. The project's success led to the first gravel road into San Clemente in 1932 and its formal designation as a municipality; soon followed service stations, campgrounds, real estate developments, a power plant and even a monastery. President Juan Perón made plans for a nearby submarine base that, though never built, resulted in a four-lane highway into San Clemente. This and continuing national prosperity led to the town's rapid development after 1950, which led to the establishment of a hospital in 1970 and of Mundo Marino in 1979, still the largest oceanarium in South America
