San Cristóbal is one of four inhabited islands in the Galápagos. It defines the easternmost boundary of the Ecuadorian archipelago. With a size of 215 square miles, it is the fifth largest island. The namesake is Saint Christopher, the Catholic patron saint of seafarers, divers and travelers. An alternative name is Chatham Island. This honors a visit to the island by William Pitt, 1st Earl of Chatham. He was an 18th century Prime Minister of Great Britain.
