"Witness" was shot at salt lake The Pool of Siloam in South Australia's Beachport, at dawn when the water was just four degrees Celsius.

The confronting ten-minute video shows the artist gasping for air as she is pushed into the water over and over again.

"Obviously, physically and emotionally it took everything," Sophia told AAP.

"We only shot it once and in a single take... it's not something that you can rehearse," she said.

The Ramsay Prize, awarded at the Art Gallery of South Australia on Friday, is Australia's biggest award for artists under 40 and comes with the same prize money as the Archibald Prize.

Sophia is a former student at the Marina Abramovic Institute in Greece, where she studied the methods of the world's most famous performance artist.

Her winning performance was a way of examining baptism and what the artist sees as its painful consequences.

The Adelaide artist, 34, saw her father baptised as a young child and felt he loved Jesus more than he loved her.

"Despite being agnostic, I responded by pretending to be incredibly devout, blindly seeking to regain his love," she said in an artist's statement.

Sophia chose South Australia's Pool of Siloam because it is where she swam as a child and is named after a biblical site where Jesus is said to have restored a man's sight, reflecting her attempts to "see" Christ like her father did.

The filming was done with another performance artist Michael Schaefer who had a keen understanding of its meaning.

"He understood to continue even even when it was very hard," Sophia said.

The performance and video show actions of vain hope can be exhaustive, violent and ultimately futile, she said.

"Ida Sophia is clearly at a pivotal point in her career - her winning work Witness is technically and conceptually resolved, capturing the breadth of her practice to this point," gallery director Rhana Devenport said.

The Ramsay Art Prize 2023 exhibition runs from Saturday until August 27 at the Art Gallery of South Australia.

Australian Associated Press