Photo by Jim Luhr, 1990 (Smithsonian Institution). A vertical aerial photograph shows the small, roughly 1-km-wide Isla San Martín, the westernmost of the small volcanoes of the San Quintín volcanic field. Isla San Martín lies 6 km off the Pacific Ocean coast from the rest of the volcanic field and consists of a small basaltic shield volcano capped by a less than 40-m-high cinder cone. The peninsula at the SE (lower right) side of the island is formed by a lava flow.