The Galapagos Islands are an archipelago of volcanic islands famous for the fact that they were unpopulated by man until the 1800s and the amazing endemic species, especially the giant tortoises which give the islands their name. The islands are a UNESCO World Heritage Site and the surrounding waters are a national park, and a biological marine reserve. Of the 18 islands Baltra, Floreana, Isabela, San Cristobal and Santa Cruz are now populated by more than 25 000 people. The original names were given by an English pirate, but the Ecuadorians have given the islands Spanish names. The Islands were made famous by Charles Darwin after he visited them on his scientific voyage on the HMS Beagle and the endemic species here contributed significantly to Darwinian Theory.