A New Zealander has become the first woman to swim across one of the most dangerous stretches of water on the planet.

It took swimmer Kim Chambers 17 hours and 12 minutes to finish the difficult swim from the Farrallon Islands to San Francisco.

Kim Chambers, who is originally from Te Kuiti. Photo: Kim Swims Website.

Her journey started on Friday night and coursed through waters home to some of the largest great white sharks in the world.

Chambers said her swim had "nudged the boundary of safety", after she began it "violently ill" and "vomiting profusely", the Guardian reported.

Four men have previously completed the swim, but Chambers is now the first woman to do it.

In July, one man abandoned his attempt to cross when his support boat spotted a four-metre great white.

The swimmer, who lives in San Francisco but grew up in Te Kuiti, told the Guardian that it was only when she saw the Golden Gate Bridge that she knew she was going to finish.

'You are really playing with the wild and the elements of the ocean,” Chambers said. 'It is very scary because of all the great white sharks out there. We are nudging the boundary of safety.

'I love the water, but there is something scary about slipping in at dark with all the sharks.”

She called it the most difficult open swim on the planet.

Chambers has completed multiple open water swims around the world including a relay across the English Channel and a relay around Manhattan, as well as solo swims of Cook Strait, Lake Tahoe, Molokai Channel and the Strait of Gibraltar.

She was a former ballerina who discovered swimming in 2009 when she had to rehabilitate from a life-threatening leg injury.

Medical experts had told her she had a one per cent chance of walking unassisted again but she set out to prove them wrong.