The U.S. Geological Survey, the National Oceanic and Atmospheric Administration, and the Connecticut Department of Environmental Protection are working together to map the sea floor along the northeastern coast of the United States. As part of the project, multibeam-echosounder data, sediment samples, and bottom photography were obtained from an area in Long Island Sound north of Duck Pond Point, New York. Three large, northeast-southwest trending bathymetric depressions, probably resulting from scour, are present in the eastern part of the study area. Elsewhere, the majority of the sea floor in the study area is covered with sand waves and megaripples that display transverse to barchanoid and bifurcated to straight-crested morphologies. Sand-wave asymmetry indicates that net sediment transport is to the west or southwest in most of the study area. Also present are small scour depressions, which are typically formed by turbulence in the lee of sand waves. Where the scour depressions were sampled and photographed, mud clasts and outcrops of underlying distal-deltaic deposits were seen in and around the depressions. Sand is the dominant lithology; only one station had gravelly sediment from within one of the large depressions. Although not verified with samples or photographs, boulders are visible in the bathymetric imagery along the southeastern part of the survey area. These coarse lag deposits reveal exposed parts along the northern flank of the 18,000-year-old Harbor Hill-Roanoke Point-Orient Point moraine segment. Photography from the study area shows many stations have rippled or megarippled floors, generally with shell debris, burrows, and crabs present.