Abstract A highstand of relative sea level occurred at 4.2 ka in Murrells Inlet on the northern coast of South Carolina. The highstand was followed by a sea-level fall of 2 m until 3.6 ka and then a slow, steady sea-level rise of 10 cm/century to the present. Although a mid-Holocene highstand has been suggested by others, it has not been well constrained. Strong differential submergence between Murrells Inlet and Santee Delta, South Carolina, has occurred over the last 4 ka, probably as a result of sediment loading by, and subsidence of, the Santee Delta system. The occurrence of the 4.2-ka highstand corresponds to the range (7-4 ka) of the mid-Holocene Hypsithermal. The rate and magnitude of the relative sea-level fluctuation are similar to those projected for future flooding and suggest that evaluation of the Hypsithermal highstand may provide an insight to projected greenhouse-effect-related change for the future.