The International Ocean Discovery Program (IODP) is now accepting applications for scientific participants on Expedition 399: Building Blocks of Life, Atlantis Massif, aboard the JOIDES Resolution. The Atlantis Massif (AM) Oceanic Core Complex (30°N, Mid-Atlantic Ridge) is one of the earliest sites recognized for the extensive exposure of ultramafic and mafic rocks at the seafloor caused by an oceanic detachment fault. The Lost City Hydrothermal Field (LCHF) is hosted in peridotite on its southern wall and vents alkaline fluids rich in H2 as a by-product of serpentinization. The AM is therefore an ideal natural laboratory for studying tectonics, magmatism, and the interaction between the ocean and lithosphere, as well as their combined influence on ocean chemistry and the subseafloor biosphere. Opportunities exist for researchers (including graduate students) in all shipboard specialties, including but not limited to sedimentologists, petrologists, micropaleontologists, paleomagnetists, petrophysicists, borehole geophysicists, igneous geochemists, inorganic geochemists, organic geochemists, and microbiologists. Application deadline: February 1, 2022. To learn more about the scientific objectives of Expedition 399, life at sea, and how to apply to sail, register in advance for the webinar on January 5, 2022 (11:00 AM EST).