RAAF No.43 (General Reconnaissance Flying Boat) Squadron was formed at Bowen in May 1943 and an advance party moved to Karumba in early June to set up the new base for the squadron. The main party left Bowen for Karumba in mid August and Catalina flying boats of 43 Squadron were based at Karumba from 24 August 1943. The former aeradio quarters (A Block) was converted to an officers’ mess and the aeradio building (B Block) became the squadron operations building. Additional facilities were requisitioned including an upgraded concrete slipway, cantilever (nose) hangar and maintenance workshops. Construction of these items was completed by early December. RAAF 34 Operational Base Unit was established at Karumba in mid December 1943. The squadron mounted its first operational patrol from Karumba on 8 September 1943. In addition to general reconnaissance duties the Catalinas of 43 Squadron were engaged in mine laying and bombing roles, convoy protection patrols and offensive operations against Japanese shipping in the eastern islands of the Netherlands East Indies. RAAF No.43 Squadron move from Karumba to Darwin in April 1944 to conduct mine laying operations throughout the Japanese controlled Netherlands East Indies.