This isolation from mainland South America has been a major factor in creating the calling card of the Galápagos: a high number of endemic species, many of which display a remarkable degree of tameness. Many of the species that flew or swam or were carried here have evolved unique adaptations, as noted by Charles Darwin in The Voyage of the Beagle (1845) – a journey that inspired the English naturalist to conceive of his evolutionary theory.
Today, the unique avian, reptile and marine life that so fascinated Darwin now captivates a stream of visitors. The Galápagos Islands have a stable climate of warm days and cooler nights with relatively low humidity, enabling tourism throughout the year. This comfortable climate is unusual for the tropics and is due to the confluence of major ocean currents in the area. The Humboldt or Peru Current brings cold water from the southern Pacific, the warm Panama Current enables tropical marine ecosystems to develop, and the nutrient-rich waters of the Cromwell or Equatorial Undercurrent well up around the islands. This unique oceanographic situation accounts for the relatively cool water temperatures, the absence of coral, the limited rainfall and the presence of the Galápagos penguin – the northernmost penguin species in the world.