A search operation is currently in progress for a 78-year-old man who was cast into the ocean when his vessel overturned near south Sydney.

Emergency crews were dispatched to Seawall Road in Port Kembla, located in the Illawarra region, after receiving reports of two individuals in the water at 1 p.m. yesterday.

The overturned boat was discovered approximately 1 kilometer to the south.

An 18-year-old man managed to swim to shore but a search was launched for the other man who was on board.

Marine Area Command Marine Rescue NSW, Surf Life Saving NSW and the Westpac Helicopter spent yesterday afternoon searching.

The search resumed at 8am today, with NSW Police divers also involved.

Part of the boat was pulled from the water about 9.30am.

It has been taken to Port Kembla boat ramp for examination, police said.