The youngest female to complete the swim, prior to Caitlin, was Stephanie Bennington, who was a little older than Gatfield at the time of her crossing, in 2007.
The title of youngest Cook Strait swimmer is held by Aditya Raut, from India, who was 11 at the time of his swim in 2005.
How does Caitlin rate her swim?
"I'm pretty proud of myself," she said today, still feeling sore from her massive effort.
"It was long and tiring. When I was swimming in the dark, I got a bit worried. I was fine most of the way. I just couldn't see in the dark. I didn't like swimming in the dark."
Gatfield and the coordinator of the swim, Philip Rush, travelled beside Caitlin in an inflatable rubber boat and a launch followed behind. She struck out from the North Island at Ohau Point.
"When she started it was windy and choppy," said Gatfield. "She pushed through that first half well and swam really, really well. That set her in good stead for the rest of the swim."
The sea shore around Perano head is a "sheer cliff," Gatfield said, "and you're swimming up against it."
It was dark for the last 45 minutes of the swim.
"There were some super tough points when it started to get dark. The sun goes down and it gets cold."
"It's pitch black and you're swimming blind. She swam to a protruding rock from the cliff face, touched that, then it was all done."
She was lifted into the boat, wrapped in blankets and promptly fell asleep.
"She was absolutely knackered."
Caitlin said she has no immediate plans to do more ocean swims.
"I'll just keep training and see what happens."
