The Galapagos Islands are a chain of volcanic islands located on either side of the equator in the Pacific Ocean. The isolated location of the islands has allowed a vast number of species to develop that are original to each island, such as the marine iguana, the blue-footed booby, the magnificent frigatebird and of course the giant Galapagos tortoise, which may live to be over one hundred years old. Studied by Charles Darwin during his historic voyage on the HMS Beagle, the island life contributed to his groundbreaking theory of evolution. Today the islands are a popular tourist destination and a UNESCO World Heritage site.