Mike Board dived to 68m in the sport's Free Immersion category, in which the finless diver pulls down and back up the dive rope.
He was competing at an event run by world champion Briton Sara Campbell’s Discover Your Depths, in Dahab, Egypt.
Board is himself a freediving instructor who runs his own freediving school on Gili Trawangan island, near Bali in Indonesia.
Even so, the Dahab event was his first serious competition attempt, after spending time at the blue-holed coastal resort training with Campbell.
“I didn’t really have any goals when I came to train with Sara in Dahab, simply to improve my own diving and become a better instructor as a result,” said Board.
“However, my progress was so fast once she taught me the mouthfill properly, the British FIM record suddenly came into view.”
Campbell commented: “Mike trained with me for three weeks and I am thrilled by his progress – he arrived a 43m diver and leaves with a really impressive national record, and is more or less touching 70m.
“He absolutely deserves this result and I look forward to seeing his name at the top of results lists in the future.”
Many of the divers at Discover Your Depths were Britons hoping to obtain places in the men’s and women’s teams to compete at the next world championships, to be held in Okinawa, Japan later this year.
Overall winner was Briton Sam Still, a former world champion in Static Apnea (pool breath hold) who was returning to freediving competition after four years out.
British team selections are expected to completed by the end of April, after further opportunities to impress at a pool competition in Liverpool on 28 March, Chepstow’s SaltFree event on 17 April, and further competition days in Dahab.
Related links
British Freediving Association
Discover Your Depths
Freedive Gili