A Swiss national who was killed by a shark while swimming in a NSW beach has been described as a former synchronised swimmer and “passionate runner”.

Livia Mulheim, 25, and her boyfriend Lukas Schindler, 26, are believed to have been filming a pod of dolphins at Kylies Beach in Crowdy Bay National Park, on the state’s Mid North Coast, when they were mauled on Thursday morning.

Mulheim was attacked by the 3m bull shark first before her partner suffered serious leg injuries trying to save her.

Schindler managed to drag his girlfriend 50m back to shore and bystanders raced to help.

Paramedics rushed to the isolated beach but Mulheim could not be saved.

According to Mulheim’s LinkedIn she had been working as an investment associate at Bellecapital, a wealth and asset management company based in Zurich.

In a post the company described Mulheim as a former synchronised swimmer and “passionate runner” who was studying her Master’s in Accounting and Finance at the University of St. Gallen.

Livia Mulheim, 25, was killed by a bull shark while swimming at Kylies Beach in NSW.Livia Mulheim, 25, was killed by a bull shark while swimming at Kylies Beach in NSW. Credit: Bellecapital / LinkedIn

She had already obtained a Bachelor of Arts from the university in Switzerland.

The Swiss couple had reportedly travelled extensively during their Australian stay, while Schindler took part in August’s Sydney marathon and had completed a course to become a diving instructor.

Schindler suffered serious leg injuries in the attack and was flown by helicopter to John Hunter Hospital in Newcastle, where he remains in a stable condition.

Lukas Schindler remains in hospital.Lukas Schindler remains in hospital. Credit: 7NEWS Kylies Beach is a remote, unpatrolled beach located at Crowdy Bay National Park.Kylies Beach is a remote, unpatrolled beach located at Crowdy Bay National Park. Credit: 7NEWS

Since the attack authorities have been monitoring the area with drumlines and drones.

There have been no signs of the shark responsible.