The 64-year-old man, whose name was not available from police yesterday, was fishing from the shore of the island when he started to experience major pains in his torso.
A Nelson couple, Marion and Bill Gilbertson, were on the coastal walk and had crossed to the island when they heard the man calling for help about 1.15pm. They found him lying among rocks.
They called to nearby fisherman Warren Lewis, who knew exactly what to do with his 39 years' experience serving with Dunedin Marine Search and Rescue.
"I dialled 111 and they sent out the rescue helicopter. I came here for a bit of R and R [rest and recreation] and fishing. I didn't know I'd be involved in a rescue."
After he made sure the man was safe and police and an ambulance were attending the ill man, Mr Lewis returned to his fishing in the hope his luck would get better.
After being treated on the island by nine medical and emergency service staff for his medical condition - severe torso pains and vomiting - the man was lifted off by helicopter and flown to Dunedin Hospital about 3.05pm.
Mrs Gilbertson said she and her husband were on holiday and had stopped at Herbert for the night, deciding yesterday to explore the coastal walk and view the sea life on the peninsula at the end of Lighthouse Rd.
"I thought it was birds at first," she said about the man's calls for help. They walked to the edge of the island and found the sick man, who told them he had started to walk back but was in so much pain he lay down and could not get back up again.
The man was a regular fisherman in the area.
Mrs Gilbertson ran to Mr Lewis, who had a cellphone and made the emergency call.
She then ran to get the sick man a blanket from the house beside the lighthouse.
Mr Lewis said the man "was none too coherent".
"I knew all the whistles and bells and what do to to get emergency services out," he said.
Hampden Constable Darrin Low said police were unable to get the man's full name before he was flown out because of his "bad condition", except he was "Barry from Kakanui".
