East coast low whips up fields of brown sea foam along storm-eroded beaches

Port Kembla Surf Lifesaving Club surrounded by sea foam. (Supplied: Jess Whittaker)

It started building with the incoming tide, driving wind, and rain pushed in from the sea by the east coast low that was tracking down the coast this week.

Mountains of frothing, tumbling foam engulfed already storm-ravaged beaches stripped of sand by churning surf.

From Port Macquarie to Port Kembla, surf clubs had front row seats to the spectacle of nature.

Lake Macquarie's Redhead Beach surf club was gradually encircled, the foam encroaching into the car park, creeping up the first floor of the building, smothering a cafe, lifeguard tower, park benches, and hand railings.

Redhead local Tony Greenland says he hasn't seen the foam this bad since the 1974 Sygna storm. (ABC Newcastle: Andrew Lobb)

Long time local and former Redhead Surf Club president Tony Greenland said he had not seen anything like it in decades, not since a massive gale in 1974 that drove the Norwegian bulk carrier Sygna aground on Stockton Beach to the north of Newcastle. 

"This is by far and away the biggest one we've seen in many years," Mr Greenland said.

Foam whipped up by the east coast low covers Redhead Beach. (ABC Newcastle: Andrew Lobb)

Opening the club this morning, Mr Greenland was met by foam stacked against the ground floor walls and the adjacent cafe being smothered.

There were excited squeals as young children marvelled at the sight of thick sea foam. (Supplied: Tash Kingelty)

Throughout the morning, onlookers came down to see the spectacle — children, parents, and grandparents — to witness the amazing natural occurrence.

But the foam was far from white and fluffy. It was tinged with brown runoff, mixing into the seawater from the recent floods, and other sticky ingredients that clung to anything it came into contact with.

Jane Williamson, an Associate Professor of marine ecology at Macquarie University and a conjoint Associate Professor at the University of Newcastle, said it was not advisable to play in or enter the foam.

"Sea foam occurs naturally. It's a perfect storm of onshore winds, big rains and heavy swells coming onshore and causing the sea foam to be in such gigantic proportions on our beaches at the moment."

Scientists advise people to stay out of the foam for health and safety reasons.  (ABC Newcastle: Andrew Lobb)

So what is in sea foam? 

"I wouldn't jump into sea foam, I must admit, particularly the brown colour. You don't know what's in it."

A large foam event in 2015 prompted warnings about the hidden dangers within, including venomous sea snakes.

The foam is expected to be around for several days before gradually breaking down.