Santa Cruz Island is one of the Galápagos Islands with an area of 986 square kilometres (381 sq mi) and a maximum altitude of 864 metres (2,835 ft).Situated in the center of the archipelago, Santa Cruz is the second largest island after Isabela. Its capital is Puerto Ayora, the most populated urban centre in the islands.
On Santa Cruz there are some small villages, whose inhabitants work in agriculture and cattle raising. This island is a large dormant volcano. It is estimated that the last eruptions occurred around a million and a half years ago. There is a gigantic lava tunnel that is over 2000 meters long on the island that many tourists visit and walk through.As a testimony to its volcanic history there are two big holes formed by the collapse of a magma chamber: Los Gemelos, or "The Twins".