From April 13-27, 2023 (Portland, Oregon, to Seattle, Washington), NOAA Ocean Exploration conducted the 2023 Shakedown + EXPRESS West Coast Exploration expedition (EX2301), a remotely operated vehicle (ROV) and Mapping expedition to shakedown the ROV, video, telepresence, seafloor mapping, and sampling operations aboard NOAA Ship Okeanos Explorer, as well as explore deep waters off the west coast of the United States. The ROV engineers tested and calibrated ROVs Deep Discoverer and Seirios motor controllers, auto position software, lighting systems, hydraulic systems, stills camera, high-definition ancillary ROV cameras, and sector-scanning sonar. Shakedown and readiness operations for the EM 304 MK II multibeam sonar system included a GNSS Azimuth Measurement Subsystem calibration, two patch tests, and a speed-noise test. Operations during this 15-day expedition included nine successful ROV dives, which were conducted in water depths ranging from 555 m to 3960 m for approximately 45:34 hours of bottom time and resulted in the collection of 92 samples. EX2301 also mapped 12,298 sq. km of seafloor (12,263 in the U.S. Exclusive Economic Zone). Data associated with this expedition have been archived and are publicly available through the NOAA archives.