Relict karstic features or sinkholes, often referred to as blue holes, are common features along continental shelves that are underlain by carbonate rich sediments and/or rocks. Several of these features occur along the west-Florida shelf within the Gulf of Mexico, including the two mentioned in Vargas and others (2022): Amberjack Hole and Green Banana Sink (hereafter referred to as Green Banana). Scientists from the U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center (USGS-SPCMSC) participated in sampling efforts lead by the National Oceanic and Atmospheric Administration (NOAA)-funded collaborative team from Mote Marine Laboratory, University of Georgia, and Florida Atlantic University. Amberjack Hole is located approximately 50 kilometers (km) west of Sarasota, Florida; it is a dome-shaped feature that extends 40 m below the seafloor (approximately 70 m total water depth). Green Banana is located approximately 80 km west of Sarasota; it is a U-shaped feature that extends 80 m or more below the seafloor (approximately 125 m total water depth). Naturally occurring radioisotopes of Radon and Radium were analyzed by utilizing samples collected from Amberjack Hole during cruises in May and September 2019, and Green Banana in September 2020. Total Radon-222 was measured using bulk water samples, while Radium-223, Radium-224, and supported Radon-222 (Radium-226) were measured from residue retained on manganese (di)oxide impregnated fibers (referred to as Mn-fibers from hereon) following exposure to seawater. Radium-223 and Radium-224 activity determined from the Mn-fibers were measured on a set of Radium Delayed Coincidence Counters (RaDeCC) as outlined in Moore and Arnold (1996). Total Radon-222 in water and supported Radon-222 (Radium-226 on Mn-fibers) were measured on radon-in-air detectors (RAD7, Durridge, Inc). Data included in Vargas and others (2022) correspond to USGS Field Activity Numbers (FAN) 2019-328-FA (19WFS01), 2019-357-FA (19WFS03), and 2020-317-FA (20WFS01); samples were acquired in May 2019, September 2019, and September 2020 respectively. Please read the full metadata record for details on data collection, dataset variables, and data quality.