The Galápagos Islands are an archipelago located in the Pacific Ocean, about 600 miles west of Ecuador. Comprising 13 main islands and numerous smaller islets, they are known for their unique biodiversity and are home to many species found nowhere else on Earth, such as the Galápagos tortoise and the marine iguana. The islands played a significant role in the development of Charles Darwin's theory of evolution by natural selection. In 1835, Darwin visited the islands and observed the distinct variations among species, which contributed to his groundbreaking work, "On the Origin of Species." Today, the Galápagos are a UNESCO World Heritage site and a popular destination for ecotourism.