Diving on Hydrothermal Vents at The East Pacific Rise Studying the unique ecosystem of deep-sea vents Vents exist because seawater penetrates the crust of the seafloor near mid-ocean ridges where magma, or lava, is near the surface. Contact with hot rocks warms the water and chemically alters it. The water loses its oxygen and picks up substances from the rocks. The hot water rises and emerges through vents on the seafloor. Although the water can exceed 100°C (212° F), it does not boil because the pressure at over 2000 m depth elevates its boiling point. The chemical changes the hot water has undergone means that it carries substances that bacteria can use as energy sources. At vents where bacteria proliferate, animals that eat bacteria congregate, as do animals that live, not by eating bacteria or anything else, but by taking energy from bacteria that grow inside their bodies.