America's reigning Olympic champion Carissa Moore was knocked out of surfing's quarter-finals by France's Johanne Defay in Tahiti on Thursday, and said she couldn't imagine a better place to call time on her storied career.

The five-time world champion skipped this year's professional tour after just missing on adding another world title to her tally last year. She said she would likely hang up her competitive rash shirt and look to start a family after the Olympics.

"I mean, you put everything you have into something. I put my whole year, I took a chance, I left the tour. I came here and spent months out of the year just trying to do my very best, and when you come up short of a dream, it sucks.

"But at the same point, like how fun was it? I wouldn't have had it any other way.

"So obviously, I'm really sad to not be a part of finals day and get to represent my home and my family one more time, but I'm really grateful," the Hawaiian said.

Moore was trailing Defay with seconds on the clock when she pulled into a tight barrel that squeezed shut and knocked her down, leaving her with a two-wave heat total of 6.5 points out of a possible 20 to Defay's 10.34.

"I couldn't have imagined a better place to finish off my career. I mean, that was the plan. I'm gonna give myself some time to just take a break.

"It's been full on - it's been full on for my whole life. And I'm really proud of that and proud of how I've given it everything," she said, tears streaming down her face and taking a moment to compose herself.

"The last thing I just want say is I want to express my gratitude to everybody who's been there for me and supported me, not only in this event, but my whole life. It's just nice to have a community behind us," said Moore, walking into a big hug from her husband Luke and a round of applause.