Location of bottom video tracklines along with videos collected in July 2016 by the U.S. Geological Survey off Town Neck Beach in Sandwich, Massachusetts, during field activity 2016-037-FA (MP4 video files and polyline shapefile)

Bottom video was acquired using the MiniSEABOSS. The observations from video and still cameras and the sediment data are used to explore the nature of the sea floor and, in conjunction with high-resolution geophysical data, to make interpretive maps of sedimentary environments and validate acoustic remote sensing data. This setup of the MiniSEABOSS incorporates a downward-looking SeaViewer 6000 HD Sea-Drop video camera with topside feed, two GoPro HERO4 Black digital cameras, a modified Van Veen sediment sampler, and a dive light. A compass and depth sensor were attached to the sampler as well and are sometimes visible in the top-mounted GoPro to be used for troubleshooting as necessary. The elements of this particular MiniSEABOSS system are held within a stainless-steel frame that measures ~1 x 1 meters. The frame has a stabilizer fin that orients the system as it drifts over the seabed. A dive light was mounted at the top of the frame and aimed downward to illuminate the seabed for photographs. One of the GoPro HERO4 Black cameras was mounted lower, approximately 40 centimeters from the bottom, on the MiniSEABOSS frame and captured bottom photos every 5 seconds and backup video, while the other was mounted higher, approximately 70 centimeters from the bottom of the frame, and recorded additional backup bottom video. Two red lasers were set 20 centimeters apart (both as they are mounted on the MiniSEABOSS frame and as seen in photographs and video on the seabed) for scale measurements. The red laser dots can usually be seen in the imagery depending on the bottom type and distance to the sea floor. A third laser is positioned at an angle so that when it intersects the other lasers, the MiniSEABOSS is at the optimum height (approximately 75 centimeters) off the bottom for a still photograph. The R/V Rafael occupied one of the target stations and the MiniSEABOSS was deployed off the vessel's starboard side. The winch operator lowered the sampler until the sea floor was observed in the top-side live video feed. The vessel and sampler drifted with wind and current for up to a few minutes to ensure a decent image with a clear view of the sea floor and then at most stations the winch operator lowered the Van Veen sampler until it rested on the sea floor. When the system was raised, the Van Veen sampler closed and collected a sample as it was lifted off the sea floor. The sampler was recovered to the deck of the survey vessel where a subsample was taken for analysis at the sediment laboratory at the USGS Woods Hole Coastal and Marine Science Center. Sediment samples were only attempted in areas where collecting a sample would not damage the MiniSEABOSS; therefore, no samples were collected in areas with a cobble, boulder, or rocky seabed, as identified in real time using the top-side live video feed. Bottom video was recorded from the downward-looking SeaViewer 6000 HD Sea-Drop video camera directly on to solid-state drive (SSD) media using an Odyssey7 video recorder. DGPS navigation from a Hemisphere DGPS receiver was logged through HYPACK navigation software and a DataBridge data logger. The DGPS was set to receive fixes at a one-second interval in geographic coordinates (WGS 84). A log file for the survey was saved in ASCII text format.