Floating transient electromagnetic (FloaTEM) data were acquired on the Rainbow Reservoir during November 2018. During the survey, approximately 12 line-kilometers were collected in the Rainbow Reservoir, near Windsor, Connecticut study area. Data were collected by members of the U.S. Geological Survey, Hydrogeophysics Branch, and New England Water Science Center. FloaTEM data acquired along the Rainbow Reservoir in Hartford County, in Connecticut, were collected to test a new continuous water-borne transient electromagnetic data collection platform, and to characterize the subsurface resistivity structure. FloaTEM data were collected using an Aarhus University HydroGeophysics Group FloaTEM unit using a transmitter loop (Tx) size, 4 by 2 meter square (m^2), in an offset-loop receiver (Rx) configuration utilizing a receiver coil that is 0.5 by 0.5 m^2 in size (with an effective area of 35 m^2) towed about 7 meters behind the Tx loop. The Tx outputs dual currents of about 3 and 30 amperes (A) for dual-moment transmission. The measurement cycles take approximately 0.5 seconds to complete and are comprised of several hundred individual transients that are averaged into 1D soundings along the profile. This data release includes the averaged, culled, and inverted FloaTEM data along the survey line that were used to produce the final resistivity models. Digital data of the processed soundings are provided, and fields are defined in a data dictionary. (1) Files with AVERAGED.xyz and AVERAGED.csv are space- and comma-delimited ASCII files that contain the least processed data where transients were averaged together and most coupled data were removed.Data locations are provided as UTM Zone 15 N projection and datum of WGS-84. (2) Files with CULLED.xyz and CULLED.csv are space- and comma- delimited ASCII files containing the processed data where negatively-impacted transients and coupled data were removed using a combination of automated and manual processing. Data locations are provided as UTM Zone 15 N projection and datum of WGS-84. (3) Files with INVERTED.xyz and INVERTED.csv are space- and comma-delimited ASCII files containing the inversion model results. Model locations are provided as UTM Zone 15 N projection and datum of WGS-84. (4) Files with WATER-DEPTH_DATA.xyz and WATER-DEPTH_DATA.csv are space- and comma-delimited ASCII files containing the water-depth data as measured from the bottom of the transducer. Water-depth measurement locations are provided as UTM Zone 15 N, WGS-84. (5) Files with INVERTED_image.png and INVERTED_image.pdf are the inverted model output as a 2D profile of electrical resistivity distribution in the subsurface.