Lauren Boyle produced the best swim by a New Zealander at the London Olympics to shatter her national record by more than three seconds to finish fourth in the 800m freestyle.
Boyle covered the 16 laps of the pool at the Aquatics Centre in 8min 22.72sec, bettering the time of 8:25.91 she set in the heats to qualify fifth fastest for the final.
"I never thought I could come fourth in the Olympics, I'm just really proud of myself," an emotional Boyle told Sky Sport.
The 24-year-old picked up a place over the last 50m but couldn't catch Great Britain's pre-race favourite Rebecca Adlington.
"I don't really care that I didn't get a medal, I'm just really happy I finished in the top eight," a crying Bolye said.
American 15-year-old Katie Ledecky won the gold while Spain's Mireia Belmonte Garcia claimed the silver medal.
Adlington was seeking to become the first British woman to retain an Olympic title, following her success in the event in Beijing four years ago.
And the 23-year-old was also bidding to be the first British woman to win three Olympic golds, having also won the 400m freestyle in Beijing.
But Ledecky established an early lead which she never relinquished, winning in 8:14.63.