Detailed bathymetric, side-scan sonar and shallow seismic surveys followed by sediment sampling were conducted in Karwar Bay, Karnataka, India to study the surficial geology with special emphasis on basement configuration for planning and development of an all-weather port. The depths in the survey area vary from 1 to 16 m. The seabed is fairly smooth and relatively steep from the shore up to 6 m, beyond which it slopes gently seaward. Sonographs indicate tidal furrows between 7 and 8.5 m, while rocks occur 0.5 km north of the approach channel at 9.5 m and NE of Karwar Head near the entrance to Baitkol Cove. Sporadically rock exposures or hard sediment patches occur mostly in the north and 0.2 to 0.3 km south of the apporach channel west of 9 m and seaward of 11 m isobaths. Seismic profiles revealed a well difined acoustic basement beyond 9 m, south of Tuming basin and near Mandal Island. The irregular basement is overlain by 12-15 m thick sediments, soft clays at the surface underlain by stiff clays or very fine sands/silts. At places it even reaches 2-3 m below the seabed. Bedrock at shallow depths at the offshore end of the approach channel and south of the Turning basin requires special underwater blasting techniques.