Leopard seals (Hydrurga leptonyx) and Ross seals (Ommatophoca rossii) produce underwater sounds during summer in the Southern Ocean. For both species, geographic differences in vocal behavior are known to occur over synoptic scales (> 1000 km), but have not been explored over smaller spatial scales. Information on spatial patterns in animal vocal divergence can provide insight in dispersal patterns and the factors that drive geographic variation. Here we explore if and how vocal behavior of leopard and Ross seals differs on a regional scale (< 900 km) in the Southern Ocean. The vocal repertoire size and composition of leopard and Ross seals were compared between two offshore (68°S 0°E, 66°S 27°W) and one coastal (70°S 8°W) location in the Atlantic sector of the Southern Ocean. Leopard seals were vocally active between October and January. Ross seal vocalizations were present in the recordings from mid-December until the end of January at all recording locations. The leopard seal vocal repertoire consisted of 8 calls at all recording locations. Predominant call type was the ‘low double trill’ (> 50%). Leopard seals showed low intra-regional variability in repertoire composition, but exhibited differences in repertoire size and composition on a synoptic scale. The vocal repertoire of Ross seals consisted of 5 call types with the ‘low siren call’ dominating (> 35%) at all recording sites. The Ross seal vocal repertoire composition differed between the three recording sites and on a synoptic scale when compared to recordings from other basins. Our findings suggest leopard seals belong to the same ‘vocal clan’ on a regional scale, likely reflecting the spatial scale of distribution during the vocally active period. Ross seals may be more stationary during the breeding season, restricting the spatial scale over which vocal interactions occur, which may result in vocal variation over smaller geographic scales.