A Quaternary stratigraphic succession preserved offshore Southeast Ireland (between Dungarvan to Hook Head) records a sequence of depositional and erosional events that supports regional glacial event models derived from nearby coastal sediment stratigraphies and landforms. Multichannel seismic and Sparker data are presented and reveal a five-fold event stratigraphy. A regionally widespread, largely acoustically massive facies (SU2) interpreted as the ‘Irish Sea Till’ infills an uneven, channelized bedrock surface overlying irregular mounds and discontinuous pockets of weakly stratified deposits (SU1) in bedrock lows that are likely remnant, earlier Pleistocene diamicts and associated sediments. SU2 is truncated throughout the study area by a strong, horizontal reflector and overlain by a thin, stratified acoustic facies (SU3), suggestive of the development of a regional ice dammed palaeolake or smaller ponded water bodies after the recession of ice. On the near shore bedrock platform to the north, a north to south oriented linear narrow ridge at seabed is interpreted as an esker, and represents southward flowing subglacial drainage associated with a restricted ice sheet advance onto the Celtic shelf postdating the SU1-SU3 seismostratigraphy. Onshore LIDaR data reveal drumlin orientations that corroborate the southerly advance of ice into the Celtic Sea from the mainland. The evidence supports palaeoglaciological models derived from nearby coastal localized sediment sequences comprising an LGM-aged cross-shelf Irish Sea Ice Sheet flow from the east, followed by proglacial subaqueous deposition, and finally an episode of offshore-directed Irish Ice Sheet ice flow at a regional scale. The offshore topography marks a new limit for a restricted Late Midlandian Irish Ice Sheet advance from an inland ice dispersal centre onto the Celtic Sea shelf offshore County Waterford.