In 2008-09, the Maritime and Coastguard Agency of the United Kingdom and the Marine Institute Ireland undertook bathymetric survey work north of Antrim, updating Admiralty charts (Joint Irish Bathymetric Survey Project). In doing so a number of interesting submarine geological features were identified around Rathlin Island, including a submerged crater or lake on a plateau with clear evidence of water courses feeding it. This suggests the events leading to inundation - subsidence of land or rising water levels - were extremely quick.