Beaches along the Mid North Coast have reopened after a shark attack claimed the life of a young Swiss woman and left her boyfriend with serious injuries.

Kylies, North Haven, and Crowdy Bay beaches were closed following the attack early on Thursday morning, when a three-metre bull shark mauled the couple while they swam at the remote Crowdy Bay National Park.

Livia Muhlheim, 25, died and her boyfriend Lukas Schindler, 26, was seriously injured in the attack.

Swiss shark attack victim Livia Muhlheim.

Shark attack survivor Lukas Schindler.

The shark bit Mr Schindler on the leg as he tried to save his girlfriend.

He managed to drag the young woman to shore with him, but she could not be saved.

The beaches reopened at 12.30pm Friday, after increased drone and jet ski surveillance showed no further threatening marine activity.

“Ahead of the weekend, and noting the forecast hot temperatures that will attract large crowds to the beaches, drones will continue to provide shark surveillance to the area, particularly at Camden Haven and Crowdy Head, with nippers set to go ahead as scheduled on Sunday,” a Surf Life Saving NSW spokesperson said.

Experts reviewing the scene say the bull shark involved is unlikely to pose an ongoing threat. Picture: iStock

The couple, both in their 20s, had arrived at a nearby campground on Wednesday.

NSW Ambulance Inspector Kirran Mowbray said the shark attacked Ms Mulheim first, and her partner “did everything he could to get them both into shore and yell out for assistance to a bystander who was there”.

A quick-thinking bystander on the beach used her swimmers to fashion a makeshift tourniquet around Mr Schindler’s leg.

“She’s essentially saved his life and bought him time before (paramedics) can get there,” Inspector Mowbray said.

The man was flown to John Hunter Hospital in critical condition.

NSW Ambulance Superintendent Josh Smyth described the incident as “tragic”.

He thanked the witnesses who jumped in to render first aid to the couple.

“The courage from some bystanders is amazing in the situation and … to put yourself out there is very heroic.

Beaches along the Mid North Coast reopened Friday after the fatal shark attack. Picture: NewsWire / Damian Shaw

Tributes as investigation continues

A swim club in Switzerland has paid tribute to Ms Mühlheim, who was a highly regarded synchronised swimmer.

She competed from a young age and later judged artistic swimming competitions.

Swim Regio Solothurn paid tribute to her lifelong love of the water in a post on their website.

“It is with deep sadness that we announce the death of Livia Mühlheim, former artistic swimmer and active judge,” the statement read.

“She died in Australia – in her beloved element, the water. On behalf of the club, we express our sincere condolences to the family.”

Authorities have been reviewing GoPro footage from the scene to better understand the attack.

Experts say the shark is unlikely to pose an ongoing threat, but drone surveillance will continue as a precaution.

Local leaders expressed their heartbreak over the tragedy.

Federal MP Alison Penfold said she was deeply heartbroken that a young woman had been killed.

“I cannot imagine the pain and shock that family and loved ones are going through right now,” she said.

“I extend my deepest condolences to them and the wider Crowdy community in what is a devastatingly tragic loss of life.”

The couple were swimming at Kylies Beach in Crowdy Bay on Thursday. Picture: NewsWire/ Scott Calvin

Port Macquarie MP Robert Dwyer expressed his condolences for the woman killed in the attack.

“This is a heartbreaking day for our community and my thoughts are with both families as they grapple with something no family should ever have to face,” he said.

“I want to thank the people who stepped in straight away and the first responders who pushed through tough conditions to do everything they could.”

Surf Life Saving NSW chief executive Steven Pearce described the location as “quite a remote location”.

“These incidents are horrific for everyone, and unfortunately, we’ve had a few this year already,” Mr Pearce said.