Uninterpreted "boomer" seismic-reflection data reveal distinct sand bodies offshore reaching over 3 m in thickness, and a much thinner section nearshore. A well-defined, high-amplitude reflection marking the base of the Holocene section (confirmed by vibracores) is easily identified beneath the sand ridges. Low-relief sand ridges in the nearshore area trend NE-SW (Twichell and others, 2000) in contrast to NW-SE sand ridge trends off Indian Rocks Beach (Harrison and others, 2000). Both types of sand ridges are oblique to the coastline and commonly show asymmetry, with the steeper lee slope facing SW (Harrison) or NW (Twichell). Also evident at 5- to 10-m depth in the subsurface are wavy reflections attributed to karst deformation in the Miocene limestone bedrock and infilled shelf valleys that are common below the inner shelf south of Tampa Bay.