Four Canberrans saved a man from drowning at a south coast beach.

Beach goers spotted a man, in his 40s, waving for help in the waters of Surf Beach, just south of Batemans Bay, about 2.30pm. He was then seen floating face down about 100m from the shore.

Two Canberrans ran in to the surf, grabbed him by the neck and lifted his head out of the water.

Another Canberran used a bodyboard to float him in to safety, while a fourth called 000.

He was still conscious, but breathed in a significant amount of water, and regurgitated for several minutes on the sand.

Paramedics, police and surf lifesavers from Batemans Bay and Broulee arrived within eight minutes, and took the man to Batemans Bay Hospital in a serious condition.

Far South Coast lifesaving director Andrew Edmunds said the man came dangerously close to drowning, and praised the efforts of the four men in saving his life.

"Any longer in the water and it would have been a very different story," Mr Edmunds said.

"They definitely saved his life, without their intervention he would have drowned."

The popular beach is not patrolled in the off season, which began this month.

Mr Edmunds said the conditions were relatively calm along most of the far south coast beaches.

"It just goes to show that even in good conditions, the ocean can still trick people and people can still find themselves in trouble, which is why you should always swim at a patrolled beach," he said.

The beaches were not overly busy, despite the Canberra Day long weekend.