Hydrothermal vents occur when sea water enters the crust and comes in contact with the volcano's magma chamber. The hot fluid becomes enriched with minerals and then emerges through the vent; when it comes in contact with the colder seawater, its minerals are deposited and create mounds and 'chimneys'. Cyanobacteria use the hot water and minerals as an energy source through a process called chemosynthesis; this vent is covered with red, white, and black bacterial mats. Image taken by the ROV Hercules developed by the Institute for Exploration at Kolumbo underwater volcano, located northeast of Santorini in the Aegean Sea. Image courtesy of the Institute for Exploration, the University of Rhode Island (URI) Graduate School of Oceanography (GSO), and the URI Institute for Archaeological Oceanography