In March 2020, the U.S. Geological Survey and the University of Puerto Rico Mayagüez (UPRM) Department of Marine Sciences conducted a marine seismic-reflection experiment focused on observing geophysical evidence of submarine faulting and mass wasting related to the southwestern Puerto Rico seismic sequence of 2019–20. The seismic sequence culminated with a magnitude 6.4 earthquake centered beneath Guayanilla Canyon on January 7, 2020 and caused shoreline subsidence, rockfalls, and considerable damage to buildings. The survey was conducted during March 7–13 out of the UPRM Isla Magueyes Laboratories aboard the research vessel Sultana. Approximately 226 line kilometers of multichannel seismic reflection data were collected across the insular shelf and upper slope of the Caribbean Sea between La Parguera and Guayanilla Bay and offshore in the vicinity of Guayanilla Canyon. The seismic profiles image up to 0.5 seconds (approximately 0.5 kilometers) of the sedimentary section beneath the sea floor and provide evidence of faults and mass wasting.