The islands, created by the southeastward movement of the Nazca plate over a geological hot spot (see plate tectonics), are largely desolate lava piles. They have little vegetation or cultivable soil except on the high volcanic mountains whose upper slopes receive heavy rains from the prevailing trade winds and are mantled by dense vegetation. The climate is modified by the cool Humboldt Current. The Galápagos are famous for their wildlife. Although the gigantic (up to 500 lb/227 kg) land tortoises the islands are named for now face extinction, there are land and sea iguanas and hosts of unusual birds, such as the flightless cormorant, which exists nowhere else, and the world's northernmost penguins. Shore lagoons teem with marine life.

The islands were discovered in 1535 by the Spaniard Tomás de Bertanga and originally known as the Encantadas. Early travelers were astonished by the tameness of the animals. In 1832 Ecuador claimed the Galápagos. Charles Darwin visited the islands (1835) during the voyage of the Beagle, and gathered an impressive body of evidence there that was used later in support of his theory of natural selection. Although buccaneers, seeking food, made inroads on the fauna, real depredations did not begin until the arrival in the 19th cent. of the whalers and then the oilers, who killed the tortoises wholesale for food and oil.

During World War II the United States maintained an air base on the islands for the defense of the Panama Canal, and in 1967 a satellite tracking station was established. On the centennial (1959) of the publication of Darwin's Origin of Species the Galápagos were declared a national park; the surrounding waters are a marine resources reserve. The Galápagos remain one of the few places in the world where naturalists can study living survivals of species arrested at various evolutionary stages. They also are an increasingly popular tourist spot.