LAUSR

Significance We describe the discovery of a large, active, high-temperature off-axis hydrothermal vent field on the East Pacific Rise. Hydrothermal vents are more prevalent across the crestal region of midocean ridges than previously thought. Our finding has important implications for understanding the fundamental controls on vent location and hydrology of hydrothermal systems along the crest of fast-spreading midocean ridges. The site provides a validation point for observations and models that call for significant hydrothermal heat loss beyond the immediate spreading axis. Finding an active off-axis vent field implies that temporally stable off-axis vent-endemic populations may provide a source of colonizing fauna to on-axis hydrothermal ecosystems after seafloor volcanic eruptions.