This website provides an account of a research cruise to the Lost City Hydrothermal Field at the summit of the Atlantis Massif. During this 32-day expedition, scientists onboard the research vessel Atlantis explored active limestone chimneys that rise 200 feet above the seafloor. This site features information about the biology, chemistry and geology of the Lost City area, as well as explanations of the instruments used to sample and analyze these parameters. It also describes how researchers used the robotic Autonomous Benthic Vehicle and three-person submarine Alvin to explore, map and sample the sea floor. The site also includes a daily shipboard journal, a glossary, and an ask-a-scientist online form. This extensive site provides in-depth, broadly accessible information about the science, mapping and operations of this expedition and hydrothermal systems in general.