Diving off Long Island in the Bahamas, Campbell dived to 96m in the sport’s Constant Weight category, in which the diver descends and ascends under fin power, carrying any choice of weight throughout.
The dive beat by just one metre the mark set last year by Russian Natalia Molchanova, who had taken the record from Campbell.
Campbell, 37, was under water for 3min 34sec. On surfacing she became light-headed but remained sharp enough to complete the surface protocol to the satisfaction of the judges from AIDA, competitive freediving’s governing body.
Campbell said that the dive had been “the toughest world record I've earned”, involving the “most challenging conditions I've ever experienced here”.
She had carried out just 17 training dives since setting three AIDA world records in categories including Constant Weight in November 2007, while still a competition freediving novice.
Campbell withdrew temporarily from competition last year, following the death of her mother.