A South African woman has been killed in a shark attack off the country's east coast, in what authorities have confirmed is the first recorded fatal shark attack of the year.

Janine Lochrenberg, 65, was swimming off Orient Beach in KuGompo City, formerly known as East London, on Tuesday morning when she was attacked at around 08:00 local time.

Lochrenberg was taking part in her daily morning swim with a local open water swimming club when the attack occurred. Fellow swimmers brought her to shore, but she is believed to have died before they could get her out of the water.

Witnesses said she was bitten in two places — on her thigh and her upper arm. She had been wearing a magnetic shark repellent band on her ankle at the time of the attack.

Her sister, Margot, said she was holding Lochrenberg's head as they brought her to shore, but believed she had bled out in the water.

"She'd made peace with that. She had a deep affinity with the water and was a remarkable person," Margot said, adding that her sister had "loved the water so much" despite being aware of an "elevated shark presence in East London."

Lochrenberg's partner, Barbara Briceland, described the retired medical physicist as a strong swimmer who often swam far out into the breakers.

"She was highly intelligent, lots of fun, kind, in a quietish way, thoughtful, well-loved with a love of life," Briceland said.

Briceland added that the two had been looking forward to retirement and were about to leave together on a three-week road trip.

Orient Beach, where the attack took place, has been closed alongside a nearby beach, authorities confirmed.

Shark attacks are rare in South Africa. According to the Florida Museum's International Shark Attack File, approximately ten fatal attacks have been recorded in the country since 2012.