One of the Galapagos Islands, eastern Pacific Ocean. It is the most populated and fertile island of the archipelago, producing sugar, coffee, cassava, and limes. Volcanic in origin and about 24 mi (39 km) long and 8 mi (13 km) wide, it is the only island of the group that has a regular supply of fresh water. Charles Darwin landed there at the settlement of San Cristóbal in 1835 and compiled data that he later used in his book On the Origin of Species (1859)