The Dunedin man, of Chinese descent and aged about 40, was fishing off rocks with a friend at Seal Point when he was dragged into the sea by a large wave about 10.50am on Saturday, police said.
He was not wearing a life jacket, but managed to stay afloat for 30 minutes while clinging to his fishing rod and yelling for help as he was pushed east by the current.
The man was eventually plucked from the water by one of three private fishing vessels which joined the search.
The Otago Regional Rescue Helicopter then transferred the man to shore.
Paramedics worked on the man before he was flown to Dunedin Hospital.
The man's rescuer, Vivienne J skipper John McLachlan, said the fisherman was lucky to be alive.
''I'd say another five minutes and he would have been ... ''Mr McLachlan had been conducting a marine navigation course near Seal Point for a group of University of Otago students when the alarm was raised.
Two helicopters carrying paramedics and Dunedin Water Rescue Squad members were dispatched, and the Dunedin Coastguard vessel launched, as a full marine rescue swung into gear.
Mr McLachlan and two other private vessels nearby also heard the call over marine radio and headed to the area.
Mr McLachlan said he first saw the fisherman's backpack floating in the water, ''and then we heard him shouting''.
The man was ''about 200m away'' from his pack, floating near breakers and rocks in a moderate 3m swell, having drifted up to 1km from Seal Point, he said.
When the vessel reached the fisherman, he was thrown a life ring and then pulled on board, Mr McLachlan said.
The man was ''knackered, to put it bluntly'', he said.
Senior Constable Lox Kellas, of Portobello, said the rescued fisherman was hypothermic but conscious and talking, and ''dead lucky'' to be alive.
The man was also fortunate his friend had been able to raise the alarm quickly, despite ''marginal'' cellphone coverage in the area, Snr Const Kellas said.
Anyone fishing off rocks should always wear a life jacket, he said.
