An Overview of the Galapagos Islands

History, Climate, and Biodiversity

Scenic View of Mountain Amidst Sea at Galapagos Islands Against Cloudy Sky

Jesse Kraft/EyeEm/Getty Images 

The Galapagos Islands are an archipelago located about 621 miles (1,000 km) from the continent of South America in the Pacific Ocean. The archipelago is composed of 19 volcanic islands that are claimed by Ecuador. The Galapagos Islands are famous for their variety of endemic (native only to the islands) wildlife that was studied by Charles Darwin during his voyage on the HMS Beagle. His visit to the islands inspired his theory of natural selection and drove his writing of On the Origin of Species which was published in 1859. Because of the variety of endemic species, the Galapagos Islands are protected by national parks and a biological marine reserve. Also, they are a UNESCO World Heritage Site.


The Galapagos Islands were first discovered by Europeans when the Spanish arrived there in 1535. Throughout the rest of the 1500s and into the early 19th century, many different European groups landed on the islands, but there were no permanent settlements until 1807.

In 1832, the islands were annexed by Ecuador and named the Archipelago of Ecuador. Shortly after that in September 1835 Robert FitzRoy and his ship the HMS Beagle arrived on the islands, and naturalist Charles Darwin began to study the area's biology and geology. During his time on the Galapagos, Darwin learned that the islands were home to new species that only seemed to live on the islands. For example, he studied mockingbirds, now known as Darwin's finches, which appeared to be different from each other on different islands. He noticed the same pattern with the tortoises of the Galapagos and these findings later led to his theory of natural selection.

In 1904 an expedition from the Academy of Sciences of California began on the islands and Rollo Beck, the expedition's leader, started collecting various materials on things like geology and zoology. In 1932 another expedition was conducted by the Academy of Sciences to collect different species.

In 1959, the Galapagos Islands became a national park, and tourism grew throughout the 1960s. Throughout the 1990s and into the 2000s, there was a period of conflict between the islands' native population and the park service. However, today the islands are still protected, and tourism still occurs.

Geography and Climate

The Galapagos Islands are located in the eastern part of the Pacific Ocean, and the closest landmass to them is Ecuador. They are also on the equator with a latitude of about 1˚40'N to 1˚36'S. There is a total distance of 137 miles (220 km) between the northernmost and southernmost islands, and the total land area of the archipelago is 3,040 square miles (7,880 sq km). In total, the archipelago is made up of 19 main islands and 120 small islands according to UNESCO. The largest islands include Isabela, Santa Cruz, Fernandina, Santiago, and San Cristobal.

The archipelago is volcanic, and as such, the islands were formed millions of years ago as a hot spot in the Earth's crust. Because of this type of formation, the larger islands are the summit of ancient, underwater volcanoes and the tallest of them are over 3,000 m from the seafloor. According to UNESCO, the western part of the Galapagos Islands is the most seismically active, while the rest of the region has eroded volcanoes. The older islands also have collapsed craters that were once the summit of these volcanoes. Also, much the Galapagos Islands are dotted with crater lakes and lava tubes, and the overall topography of the islands varies.

The climate of the Galapagos Islands also varies based on the island and although it is located in a tropical region on the equator, a cold ocean current, the Humboldt Current, brings cold water near the islands which causes a cooler, wetter climate. In general, from June to November is the coldest and windiest time of the year and it is not uncommon for the islands to be covered in fog. By contrast from December to May, the islands experience little wind and sunny skies, but there are also strong rain storms during this time.

Biodiversity and Conservation

The most famous aspect of the Galapagos Islands is its unique biodiversity. There are many different endemic birds, reptiles and invertebrate species and the majority of these species are endangered. Some of these species include the Galapagos giant tortoise which has 11 different subspecies throughout the islands, a variety of iguanas (both land-based and marine), 57 types of bird, 26 of which are endemic to the islands. Also, some of these endemic birds are flightless such as the Galapagos flightless cormorant.
There are only six native species of mammal on the Galapagos Islands, and these include the Galapagos fur seal, the Galapagos sea lion as well as rats and bats. The waters surrounding the islands are also highly biodiverse with different species of shark and rays. Also, the endangered green sea turtle, hawksbill sea turtle commonly nest on the beaches of the islands.
Because of the endangered and endemic species on the Galapagos Islands, the islands themselves and the waters surrounding them are the subjects of many different conservation efforts. The islands are home to many national parks, and in 1978 they became a World Heritage Site.


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Briney, Amanda. "An Overview of the Galapagos Islands." ThoughtCo, Apr. 5, 2023, Briney, Amanda. (2023, April 5). An Overview of the Galapagos Islands. Retrieved from Briney, Amanda. "An Overview of the Galapagos Islands." ThoughtCo. (accessed June 7, 2023).