The Neptune swimmer finished the women’s 1500m freestyle in 16min 37.01sec as the national championships began in Auckland.
It left her 5sec off guaranteed qualification for the Tokyo Games in the event.
However, it was a classy display nonetheless and the 21-year-old bagged a silver medal.
She trailed in Phoenix’s Hayley McIntosh by 2sec.
Fellow Neptune swimmer Ruby Heath finished fifth in 17min 33.14sec.
The Olympic qualifying times are set so each country can send two swimmers who swim beneath that time in each event.
The championships began with two races last night — the men’s 800m freestyle was won by New Plymouth’s Zac Reid.
While the 1500m was where Deans was closest to the qualifying time, she will have more opportunities as the week continues — especially in the 800m freestyle.
The event continues tomorrow with more Dunedin swimmers in action.
Notable among Neptune’s swimmers will be Erika Fairweather in the 50m freestyle and Luan Grobbelaar in the 400m IM.
The preliminaries run in the morning, before the finals from 7.15pm.
The championships run until Saturday.
