As part of the HOV Alvin 6500m upgrade, the deep submergence science community is seeking applicants to participate in the NSF sponsored HOV Alvin Science Verification Expedition (SVE). The primary objective of the SVE is to test and validate the submarine systems used for science operations. Opportunistic science will also be accomplished on the expedition, including the operation of a night program using an autonomous CTD/lander for water sampling, acoustic monitoring, and imaging at hadal depths. The SVE will take place in October following Navy certification of the submarine for diving to 6500m depth. The expedition will depart from San Juan, Puerto Rico and will conduct ~5 dives at targets that may include seaward and landward trench surfaces, potential methane seeps, and fault exposures in the trench. The expedition will then transit to the Mid-Cayman Spreading Center, where ~5 dives will be conducted on targets that may include high-temperature hydrothermal vents, volcanic features, detachment fault surfaces, and transform faults. We are seeking a diverse group of participants that span disciplinary fields, both with and without previous Alvin experience.  Because the at-sea participation may be limited due to COVID-19 restrictions, the SVE will have both ship-based and shore-based, via a high-bandwidth ship to shore connection, participation. The deadline for applications is May 28, 2021.