Detective Sergeant Jason von Tunk, of the Portland police crime investigation unit, said the body of Sean Mielnik, 46, was discovered by commercial fishermen at 9.20am on Wednesday, one nautical mile south of the Cape Nelson Lighthouse.

He said the sea conditions were extremely rough with the swell running at between 4.5 and six metres.

"The conditions were particularly treacherous," he said.

"It was extremely high risk rock fishing in that area in those conditions. It's OK on a calm day, but he should just not have been there on Wednesday."

Detective Sergeant von Tunk said waves were crashing more than 10 metres up the 20-metre cliff face.

"You only need a little bit to go wrong when it's like that to finish with tragic results," he said.

"Mr Mielnik has been fishing for a long time but it was high-risk for even the most experienced fisherman."

The investigator said there were some rules to follow, which Mr Mielnik had not observed.

"You need to let someone know where you are going and what time you expect to be back. Those guidelines were not followed," Detective Sergeant von Tunk said.

"It was only luck that his body was found by commercial fishermen pretty quickly and we were able to work backwards. If his body had not been found for some time it would have been far more difficult."

Detective Sergeant von Tunk said he was still getting over the boat trip in the rough conditions.

Mr Mielnik was from the Adelaide suburb of Albert Park.

A report into the circumstances surrounding his death will be prepared for the Victorian Coroner.

His Ford Futura stationwagon was found in the Cape Nelson Lighthouse car park.

The vehicle was taken to the Portland police station where it was examined.

He is believed to have been swept off rocks at a spot known as Snakes And Ladders, which locals regard as very dangerous when there is a big swell.

Relatives of the Albert Park man have been informed of his death by South Australian police.

At 9am: The body of a man found near Portland on Wednesday is believed to be that of a 46-year-old rock fisherman from Adelaide suburb Albert Park.

Portland police are investigating but at this stage there appears to be no suspicious circumstances.

A report will be prepared for the Victorian Coroner.

The body of Sean Mielnik, 46, was discovered by commercial fishermen at 9.20am on Wednesday one nautical mile south of the Cape Nelson Lighthouse.

It does not appear that he had been in the water long.

His car, a Ford Futura stationwagon, was found in the Cape Nelson Lighthouse car park.

It's believed the man was fishing off rocks at a spot known as Snakes And Ladders when he was swept into the water.

Detective Sergeant Jason von Tunk, of the Portland police crime investigation unit, said the sea conditions were extremely rough with the swell between 4.5 and six metres.

"Relatives of the Albert Park man have been informed by South Australian police," he said.

The station wagon was taken to the Portland police station where it was examined.

Wednesday: A body found near the Cape Nelson lighthouse on Wednesday morning is yet to be identified.

Police are at the scene after it was found about 9.30am in water at Portland.

The man is yet to be formally identified.

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