An overview of the Galapagos Islands. They are produced by volcanic activity caused by magma upwelling at the Galapagos hotspot. Large craters can be seen where the most recent eruptions have occurred, including in 2005 at Sierra Negra near the south end of the largest island. Green to white indicates the coastline, outside this is below sea level. Image produced by Ken Macdonald using GeoMapApp courtesy of Lamont Doherty Earth Observatory.