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The seafloor depths under the Cook Ice Shelf and Ninnis Glacier Tongue have not been directly measured, despite their importance for understanding ocean circulation and ice shelf change. We model the bathymetry underneath the floating ice and surrounding ocean using airborne gravity data. Our model is constrained by few ship‐based seafloor measurements near the ice front and by ice‐base measurements over areas of grounded ice from radar data. Localized basins (∼1,400 m deep) are found beneath both ice shelves. The shallowest modeled bathymetry (∼200 m) represents the offshore extension of Cape Freshfield. Near the grounding line, seafloor depths are found to be deeper than the observed depth of the modified Circumpolar Deep water in the region (<350 m), key factor for basal melt analyses. From transit flight gravity anomalies, we suggest the relocation of the mapped edge of the continental shelf and a narrowing of the Cook Shelf Depression. Plain Language Summary: The knowledge of how deep the ocean floor is under the floating ice shelves that connect to grounded ice sheets, is crucial for understanding how ocean water circulates and interacts with the overlying ice. We present a new bathymetric model of the seafloor beneath two ice shelves located in East Antarctica: Cook Ice Shelf and Ninnis Glacier Tongue. Both ice shelves are inaccessible to ships due to heavy sea ice conditions, so the data used in our model were collected from airborne surveys. Our bathymetry model shows new information on the depth and shape of the seafloor that will help understanding the ocean circulation in the area and how this might impact ice thickness changes. Key Points: High resolution bathymetry model of Cook Ice Shelf, Ninnis Glacier Tongue, and surrounding open ocean from airborne gravity inversionNew bathymetry model improves the understanding of water pathways between the ice shelves and the continental shelf edgeTransit flight gravity anomalies suggest relocation of the edge of the continental shelf northwards of the currently attributed position [ABSTRACT FROM AUTHOR]

George VI Sound is an ~600 km‐long curvilinear channel on the west coast of the southern Antarctic Peninsula separating Alexander Island from Palmer Land. The Sound is a geologically complex region presently covered by the George VI Ice Shelf. Here we model the bathymetry using aerogravity data. Our model is constrained by water depths from seismic measurements. We present a crustal density model for the region, propose a relocation for a major fault in the Sound, and reveal a dense body, ~200 km long, flanking the Palmer Land side. The southern half of the Sound consists of two distinct basins ~1,100 m deep, separated by a −650 m‐deep ridge. This constricting ridge presents a potential barrier to ocean circulation beneath the ice shelf and may account for observed differences in temperature‐salinity (T‐S) profiles. Plain Language Summary: Knowing the seafloor depth beneath ice shelves is crucial for understanding the interaction between the ocean and the overlying ice, as the shape of the sea floor influences water circulation pathways. We present a new bathymetric model of the seafloor beneath George VI Ice Shelf on the Antarctica Peninsula. The data for our model were collected from airborne surveys, including the ice surface elevation, ice thickness, and gravity field measurements. We first present a new geological model of the Sound and use our improved data coverage to relocate a previously interpreted geological fault. The new bathymetry model shows that in the southern segment of the Sound, an area with shallow bathymetry and deep ice might be acting as a barrier to the water flow. This information can change our understanding of the circulation between the northern and southern segments of the Sound and can be used in models of how this impacts the melt in the base of the ice shelf. Key Points: We present an improved resolution of bathymetry over George VI Sound from airborne gravity inversionNew crustal density model across the Sound allows relocation of a major fault and reveals a dense body on the Palmer Land side of the SoundA newly identified ridge appears to act as a constriction to ocean circulation between the southern and northern segments of the Sound [ABSTRACT FROM AUTHOR]