Very High Resolution (VHR) 3D seismic data were collected on the Adriatic shelf offshore the city of Ortona in order to define the small-scale geometric complexity of late Holocene deposits. Three groups of units are distinguished from the bottom up: (1) units U1 to U3 forming the Transgressive System Tract (TST); (2) units U4 and U5 representing the condensed interval deposited on the Maximum flooding surface (MFS) and the basal unit of the High stand System Tract (HST); and (3) U6 to U 10 forming the progradational units of the HST. The muddy HST deposits show seafloor and subsurface sedimentary features over up to 40% of its extent on the Adriatic shelf. In the area offshore Ortona, the HST shows shore-parallel undulations in water depth of ca. 30-70 m and mud reliefs in water depth of ca. 70-110 m. The mud reliefs are subcircular in plan view and occur in swarms, perpendicular to the regional contour, that are connected to each other by shore-parallel junctions. The genesis of these features is interpreted as a combination of two different mechanisms: (1) sediment deformation in relation with the condensed section; and (2) depositional process related to shore-parallel currents interacting with topographic irregularities. The evolution of the HST sedimentary pattern is closely related to a "key unit" (U5) that influences both the seaward transition from linear to complex features and the stacking pattern.