The second Australian Professional Ocean Lifeguard Association (APOLA) Stanwell Park to Wollongong Harbour swim was held on Sunday.

The first of 13 lifeguards jumped in the water at 6am and swam a two-kilometre relay leg before tagging the next.

Favourable conditions saw the final swimmers arrive at Belmore Basin about 1.30pm, ending the 26-kilometre ocean trek.

Swim director - and senior lifeguard at Stanwell Park - John Boyle said the swimmers, who were all APOLA members and worked for Wollongong City Council, battled a swell of just under two metres.

"We had a fair bit of swell and current moving around out there [on Sunday], so it was really good for it to all go off without a hitch," he said.

"It could have been a lot worse."

The council is responsible for more than 42 kilometres of coast and its lifeguards are often forced to respond to incidents outside the 17 patrolled beaches.

"We get together at this time of year to do [the swim] ... so we can have a bit of a platform to advise people of the importance of swimming at patrolled locations," Mr Boyle said.

"The idea of doing it is that lifeguards are fresh in the mind of beachgoers when they go to the beach."

Mr Boyle said "a lot of major incidents" occurred during the Christmas holiday period.

"We do our best to try and deal with them [swimmers]," he said.