Peninsula Valdés is a peninsula along the Atlantic coast in the Chubut Province, Argentina. Its size is about 3625 km².

Most of the peninsula is barren land with some salt water lakes. The largest of these lakes is at an elevation of about 40 m below sea level, the lowest elevation in Argentina and South America.

Peninsula Valdés is an important nature reserve which was listed as World Heritage Site by the UNESCO in 1999. The coastline is inhabited by marine mammals, like eared seals and elephant seals. Southern right wales can be found in the Golfo Nuevo between the peninsula and the Patagonian mainland. These baleen whales come here during the second half of the year, for mating and reproduction, because the water in the gulf is more quiet and warmer than in the open sea. Orcas can be found off the coast, in the open sea off the peninsula. The inner part of the peninsula is inhabited by nandus, guanacos and maras.