A Sydney man has been winched to safety with serious injuries after falling 20 metres down a rock ledge at a beach north of Batemans Bay on Sunday morning.

Westpac Life Saver Helicopter CEO Stephen Leahy said the 25-year-old man was rock fishing at Richmond Beach, north of Maloneys Beach, when he slipped and fell onto a rocky outcrop below.

Mr Leahy said the man slid 15 metres down a rock face before free-falling for five metres onto the ledge below.

The main sustained spinal, pelvic and leg injuries and was flown by Toll Air Ambulance to St George Hospital in a serious but stable condition.

Mr Leahy said Lifesaver 23 carried out a quick search of the area before finding the man on the rocks. He said the man couldn't move apart from waving one arm to signal the rescue crew.

"He was certainly very lucky. The potential for catastrophic injuries was very possible," Mr Leahy said.

NSW Police, Fire and Rescue NSW and Far South Coast Lifesaving crews were also involved in the operation.

Batemans Bay Post