During the Okeanos Explorer (EX) mission EX1204, the vessel will sail from Norfolk, VA, along the continental shelf break of the U.S. East Coast from Virginia to Rhode Island, to the ship’s home port of Davisville, RI. The goal of the mission is to explore northeastern canyons and continental margins using the ship’s Kongsberg EM302 multibeam sonar, Simrad EK60, and Knudsen sub-bottom profiler. CTD casts are probable around different locations around the axis of the canyons with niskin bottle firings for water sampling, depending upon staff availability. XBT casts will be fired every 4 hours for system calibration checks. Multibeam data collected in a sloped but featureless area in the vicinity of McMaster canyon will be used in comparison with data in this same area recorded by the NOAA Ship Hassler and the NOAA Ship Bigelow.