68 Holocene-aged corals from reef cores collected throughout the Florida Keys reef tract (FKRT) were dated using a combination of U-series and radiocarbon techniques to quantify the millennial-scale variability in the local radiocarbon reservoir age (ΔR) of the shallow water environments of south Florida. ΔR provides a measure of the deviation of local radiocarbon concentrations of marine environments from the global average and can be used as a tracer of oceanic circulation and local hydrology. U.S. Geological Survey (USGS) scientists combined coral-based estimates of ΔR, using statistical modeling, to reconstruct millennial-scale variability in ΔR at locations on the FKRT with (“nearshore”) and without (“open ocean”) terrestrial influence. USGS scientists also used the models to provide temporally-explicit estimates of ΔR that can be used in radiocarbon calibrations of marine samples from the region. In Version 1.0 of the USGS data release (Toth and others, 2017) associated with this metadata record, derivedthe coral-based estimates of ΔR were derived using data from the Marine13 radiocarbon calibration curve (Reimer and others, 2013). In version 2.0, the ΔR estimates were instead derived using the Marine20 radiocarbon calibration curve (Heaton and others, 2020). For further information regarding data collection and analysis methods refer to Toth and others (2017).