Abstract Much about the offshore California Continental Borderland remains unknown, despite its location off the most populated area of the west coast of North America, vital importance to US interests, and potential for seismic and tsunamigenic hazards. In 2015 and 2016, Exploration Vessel (E/V) Nautilus of the Ocean Exploration Trust undertook a series of seven expeditions in that region. During those cruises, we acquired 13,075 km 2 of multibeam bathymetric data, performed 58 dives with remotely operated vehicles (ROV) Hercules and Argus , totaling 500+ hours underwater (1000+ hours of video), and collected 532 geological and biological samples across this 200-km-wide, tectonically active region. Because Nautilus is equipped with state-of-the-art telepresence technology, numerous scientists based on shore actively participated in these expeditions in real time. Here, we describe the data acquired during these expeditions and present some very preliminary results. The digital data and physical samples are accessible to the scientific community via online request systems.

The August 2007 expedition to the Black Sea continued a multiyear project designed to locate and study ancient shipwrecks in deep water. The expedition revisited and investigated two shipwrecks, Sinop D (at 325 m depth off Sinop, Turkey) and Chersonesos A (at 135 m depth off Sevastopol, Ukraine). These wreck sites are good case studies for our research because they are located in different parts of the Black Sea, in anoxic and suboxic waters, respectively. Preliminary data reported here are from seawater samples taken from around the wrecks and a year-long collection of temperature, salinity, and pressure data. Trace-element data from the seawater samples are consistent with reported processes and values for the Black Sea. The oceanographic sensor data confirm the stagnant nature of the anoxic water layer that has allowed for the high level of preservation of the Sinop D wreck site. We also discuss the design and placement of two sets of experiments left in situ to characterize the decay rates of common materials found on ancient shipwrecks, including wood and metal. By providing ways to understand the chemical and physical processes that characterize different parts of the Black Sea water column, these wrecks are important sites for (1) determining the preservation potentials of cultural materials in deep water, and (2) informing the design of methodologies necessary to conserve them.