Crosland (28), a marketing student at the University of Otago, took nearly 1sec off the old record when he won the men's aged 25 to 29 100m backstroke in 55.87sec.
It was 1sec second slower than his personal best time, set at an open event.
''But the time was good because we are on a training break at the moment,'' Crosland said, ''It's good to know that is where I'm at for the start of the new season. It's definitely a good feeling to break a world record but I haven't really thought about it too much.''
Crosland was a talented teenage swimmer with Duncan Laing's squad. He then had a long time away from competitive swimming until he started back with Gennadiy Labara's Osca squad two years ago.
The time qualified him for the World University Games in Russia in July.
Crosland had his first taste of international competition at the Oceania championships in New Caledonia last year. He won a gold medal and five silver medals.
Crosland has made a dramatic improvement over the last 12 months and has broken numerous Otago records.
At the open national long-course championships in Auckland, he won two silver and two bronze medals and three relay medals.
''I would put it all down to Gennadiy and his hard work ethic in training,'' he said.
''I just follow what he told me to do and it works. He's a good guy to have in our team.''
Crosland has been nominated for five events at the World University Games: 50m (best time 25.89sec), 100m (54.70sec) and 200m backstroke (2min 00.12sec), 200m individual medley (2min 4.39sec) and 50m freestyle (23.86sec).
His long-term goal is to qualify for next year's Commonwealth Games in the 100m and 200m backstroke.
Former international Rebecca Perrott (Levin) broke five New Zealand masters records in the women's aged 50 to 54 grade.
She won four medals - gold, silver and two bronze - at the 1978 Commonwealth Games in Edmonton. She was 15 when she competed at the Montreal Olympic Games in 1976 and is still the youngest competitor to represent New Zealand at the Olympics.
Kieran Garbutt, the president of the Dunedin Masters Swimming Club, emphasised that any record set at the New Zealand masters swimming championships last weekend was provisional until it was ratified by the New Zealand Masters Swimming Association.
It was a successful weekend for the Sonntag husband and wife team that broke four records.
Lenore won the women's aged 75 to 79 50m butterfly in 59.50sec and the 200m individual medley in 4min 32.48sec. Forbes won the men's aged 80 to 84 100m freestyle in 1min 34.23sec and the 50m freestyle in 37.98sec.
Steve Prescott broke the men's aged 55 to 59 New Zealand record in the 200m butterfly (2min 50.20sec).
The women's aged 160 to 199 years (combined) medley relay team of Anne Gray, Steph Laughton, Katie Price and Steph Wahab set a record of 2min 26.08sec.
