A man has been bitten by a shark near a popular campground, taking the number of attacks in NSW in recent days to four.
The 39-year-old was taken to hospital after being bitten at Point Plomer, north of Port Macquarie on the mid-north coast, on Tuesday morning.
It was the fourth attack on NSW's coastlines since Sunday, leading to a swathe of beaches being closed.
Two people have been left with critical injuries after shark bites in two Sydney incidents.
The latest victim was in a stable condition at Kempsey Hospital, a Mid North Coast Local Health District spokeswoman confirmed.
Emergency services had no record of transporting the man to hospital, with reports suggesting a witness on the beach drove him there.
A number of beaches in the local area, which includes surfing hotspot Crescent Head, have been closed.
Paramedics earlier revealed a Formula One-style pit stop to deliver extra blood might have saved the life of a man mauled in Sydney's north on Monday evening.
The man, aged in his 20s, was bitten at Manly's North Steyne Beach and underwent surgery for severe lower-leg injuries.
He remains in Royal North Shore Hospital in a critical condition after requiring 13 units of blood at the beach and during the drive to hospital.
Such was the extent of the man's heavy blood loss, highway police met treating paramedics en route to drop extra supplies.
"They said it was almost like an Formula One pit stop of 10 seconds or less where they just opened the door, blood went in and then they continued on," NSW Ambulance acting superintendent Christie Marks said.
"This is something that doesn't happen a lot ... that is going to give him the best chance of surviving."
A 13-year-old boy was attacked while swimming in Vaucluse in Sydney's east on Sunday, requiring surgery for severe injuries to both legs.
An 11-year-old boy narrowly avoided injury at Dee Why, with a shark taking a chunk out of his surfboard on Monday morning.
In response, all of the city's northern beaches have been closed for at least 48 hours.
More than 30 SMART drumlines have been deployed along that stretch of coast, while shark listening stations and aerial surveillance have been ramped up.
Surf Life Saving NSW chief executive Steven Pearce said the "turbid and brackish" water created prime conditions for bull shark activity.
University of Sydney public policy expert Chris Pepin-Neff, who has written a book on shark policy, suggested Sydney Harbour's 100-year-old sewage pipes were likely to blame.
The pipes overflow with just 20mm of rain. More than 120mm fell on Sunday.
"When the pipes overflow, when there's more sewage, the bait fish eat the sewage and then the bull sharks come to eat the bait fish, and that draws them into the surface and into the shore," Associate Professor Pepin-Neff told AAP.
"Three shark bites in two days suggests to me there's a unique environmental condition that is more than just the heavy rain."
State officials are working to identify the species of shark involved in each incident.