Amanda Reason of Etobicoke, Ont., broke the world record in the women's 50-metre breaststroke Wednesday in Montreal.
Reason, 15, clocked 30.23 seconds at the Canadian trials for the world aquatics championships, to be held in Rome from July 19 to Aug. 2.
The old mark of 30.31 seconds was set by Australia's Jade Edmistone in 2006.
"This is just amazing," Reason said. "I'm speechless, incredible.
"My coach said I had to go out fast and get my head into the motion. I did that well in the beginning and kept pushing it through to the end and I did it."
Reason is the first Canadian female to break a world record in a long course pool since Allison Higson accomplished the feat in the 200-metre breaststroke in 1988.
Earlier Wednesday, Scott Dickens of Vancouver set a Canadian record in the men's 50-metre breaststroke, swimming the distance in 27.81 seconds to eclipse the previous mark of 28.22 held by Edmonton's Morgan Knabe since 2003.
"That swim felt great," said Dickens, who shattered the short course national records in the 50- and 100-metre breaststroke earlier this season.
"It was a nice controlled, powerful swim. The record wasn't something I was focused on, but it is nice to get."
Canada can qualify a maximum of two swimmers per event for the worlds, and extra swimmers for the relays.