The Lost City Hydrothermal Field, often referred to simply as Lost City, is an area of marine alkaline hydrothermal vents located on the Atlantis Massif at the intersection between the Mid-Atlantic Ridge and the Atlantis Transform Fault, in the Atlantic Ocean. It is a long-lived site of active and inactive ultramafic-hosted serpentinization, abiotically producing many simple molecules such as methane and hydrogen which are fundamental to microbial life. As such it has generated scientific interest as a prime location for investigating the origin of life on Earth and other planets similar to it. Expedition history The Lost City was first identified on December 4, 2000, using DSV Alvin and ROV ArgoII on cruise AT03-60 of the RV Atlantis. The cruise lasted 34 days, during which photographs and vent chimney samples were taken. The discovery of the Lost City prompted the National Science Foundation to fund a second, 32-day voyage (AT07-34) to the site in 2003 in order to use Alvin and the autonomous vehicle ABE with a greater emphasis on scientific sampling and creating a high-resolution bathymetric map of the vent field. ABE would participate in a combined 17 dive expeditions including follow-up visits, creating a bathymetry profile for of the massif. The first visit by the Integrated Ocean Drilling Program took place with Expedition 304 in late 2004, when a series of holes were drilled into the Atlantis Massif to collect large cores of rock from the site. Expedition 305 followed suit in early 2005, and 340T in 2012. In July 2005, Lost City was explored for nine days by Hercules and Argus on the National Oceanic and Atmospheric Administration vessel Ronald H. Brown, with video streamed live to the University of Washington in Seattle. Lost City was also explored on cruise 50 of the Akademik Mstislav Keldysh, which had a greater emphasis on exploring downslope south of the vent field. The RV Knorr sailed to the Atlantis Massif in May that year for hydroacoustic measurements of potential seismic activity. Furthermore, the French EXOMAR cruise on the vessel L'Atalante was conducted in July and August 2005 to study extremophile biodiversity in deep-ocean environments. 2015 saw a visit from the International Ocean Discovery Program Expedition 357, which emphasized drilling on the Atlantis Massif to explore off-axis circulation. A series of boreholes were left behind after cores from nine different sites were taken, which were sampled by Niskin bottles. Borehole plugs