Fire Island, New York (NY) is a 50-kilometer (km) long barrier island system fronting the southern coast of Long Island, NY with relatively complex geology. In 2016, the U.S. Geological Survey (USGS) conducted ground penetrating radar (GPR) surveys and sediment sampling at Fire Island to characterize and quantify spatial variability in the subaerial geology (Forde and others, 2018; Buster and others, 2018). These surveys, in combination with historical data, allowed for a preliminary reconstruction of the barrier’s long-term evolution. In 2021, scientists from the USGS New York Water Science Center (NYWSC), on behalf of the USGS St. Petersburg Coastal and Marine Science Center (SPCMSC), conducted additional GPR and sediment sampling surveys at Point O' Woods (POW) and Ho-Hum Beach (HHB) on Fire Island to fill in gaps in the timeline of Fire Island’s development and illuminate relationships between different geomorphic structures observed along the island. This information will be used to calibrate a model of barrier island development, quantifying historic sediment fluxes within the Fire Island system.