The attack occurred in the early hours at Crowdy Bay, about 250 kilometres (155 miles) north of Sydney, News.Az reports, citing foreign media.
The woman died at the scene, while the man sustained serious leg injuries and was airlifted to a hospital, where his condition is now stable.
“They were known to each other, and they were going for a swim when the shark attacked,” New South Wales Police inspector Timothy Bayly said.
A bystander reportedly saved the man by wrapping a makeshift tourniquet around his leg. State ambulance inspector Joshua Smyth praised the courage of the passerby as “really heroic.”
Steven Pearce, chief executive of Surf Life Saving NSW, described the incident as “a really, really terrible incident,” noting the area’s remoteness and lack of lifeguard services. Authorities confirmed that a bull shark, one of the deadliest predatory species, was likely involved in the attack.
Assessments are usually made by examining bite marks, animal behaviour, any recent sightings or ocean conditions leading up to the incident.
Bull sharks are the only one of the cartilaginous fish that are able to move between fresh and salt water, allowing them to swim vast distances.
They can grow up to 2.3 metres (7.5 feet) and are among the species of shark most likely to bite oceangoers in Australia, alongside the great white and tiger.
There have been more than 1,280 shark incidents around Australia since 1791, of which more than 250 resulted in death, according to a database of the predators' encounters with humans.
Of the total number of recorded incidents since records began, 212 involved bull sharks.
Increasingly crowded waters and rising ocean temperatures that appear to be swaying sharks' migratory patterns may be contributing to an escalation in attacks despite overfishing depleting some species, scientists say.
In September, a great white mauled a surfer to death at a popular Sydney beach.
The man, who left a wife and young daughter, lost "a number of limbs" and his surfboard was broken in two, police said.
Australia's oceans are teeming with sharks, with great whites topping the list of species that might fatally bite a human.
Though still relatively rare, fatal attacks do appear to be on the rise with 56 reported deaths in the 25 years to 2025 compared to 27 deaths in the previous quarter-century.
Undeterred, Australians flock to the sea in huge numbers -- with a 2024 survey showing nearly two-thirds of the population made a total of 650 million coastal visits in a single year.
How best to protect people from sharks is a touchy topic in Australia.
Authorities have adopted a multi-layered approach -- deploying drones, fixing acoustic trackers to sharks so they can be detected by listening buoys near popular beaches, alerting people in real time with a mobile app and stringing up old-fashioned nets.
Researchers say shark lives, too, need protecting.
Globally, about 37 percent of oceanic shark and ray species are now listed as either endangered or critically endangered by the International Union for Conservation of Nature, a database for threatened species.
