A young man who was fishing off rocks without a life jacket has died after being swept into the ocean this morning.

Two men, aged 31 and 37 years old, who were wearing life jackets had jumped into the water to rescue the 23-year-old.

Emergency services pulled the three men from waters off Blue Fish Point at Manly at 6:30am.

The younger man, believed to be a foreign national, could not be revived.

Surf Life Saving NSW said the conditions at Blue Fish Point were "challenging" with a one metre swell breaking over the rocks.

The other two men were transferred to St Vincent's Hospital in Darlinghurst.

In a separate incident, just half an hour later, another angler was rescued after falling from rocks at Cape Solander near Kurnell and the southern Sydney beaches.

That 20-year-old fisherman also was not wearing a life jacket.

He was rescued after being thrown a floatation device and taken to St George Hospital.

Life-jacket trial only in one NSW council area

Rock fishing is one of the most dangerous sports in Australia, with the majority of deaths off the NSW coastline.

After a coronial inquiry into a spate of rock fishing deaths, Deputy State Coroner Carmel Forbes recommended the state government make it compulsory for rock fishers to wear life jackets in 2015.

The state's former premier and former emergency services minister introduced the compulsory life jacket legislation last year.

Initially, the trial for compulsory life jackets was going to be statewide, but was scaled back to the Randwick Council area which contains Coogee and Maroubra beaches.

The Randwick coastline saw 17 anglers lose their lives in a decade, according to the NSW Government.

Eventually, rock fishers not wearing life jackets in the Randwick local government area will be fined $100, but there is still a 12-month grace period in place for anglers.

The trial started on December 1 and no other councils have yet taken up the option to trial the life jacket laws.

Opposition to life jackets 'disappointing'

Surf Life Saving said the two Sunday incidents added to the "frustrations of the lifesaving community" and have called for the mandatory life jacket trial to be extended statewide.

"From a lifesaving perspective, any initiative that makes this recreational activity safer is something that we strongly support," Liam Howitt from Surf Life Saving said.

"All of our members are actually volunteers, so these people who are called out to rock fishing incidents, it does have an impact on them."

Mr Howitt said there was push back from rock fishers about bringing in compulsory life jackets.

"There's certainly those within the rock fishing community who are being very vocal in their opposition to mandatory lifejackets," he said.

"There is a very real danger of this hijacking the debate and it's getting in the way of public safety and it's time for us to have an open and honest conversation about the reality that lifejackets do save lives."