The Bay of Sullivan is on the southeast of the Island of Santiago. Sullivan Bay has a length of 1.5 km with an estimated travel time of one and a half hours, covered by Pahoehoe lava flows (solidified lava in a wavy shape).
Years of the 19th century Sullivan lava was in 1897. This flow is geologically very young, the magma formed is flat, but the movement of underground lava, rapid cooling, and other eruptions led to breakage in many places.