It was world champion Lauren Boyle who took the limelight on the first day of action.
She was one of four swimmers to go under the qualifying time for July's FINA World Championships at the West Wave Aquatic Centre in Henderson, a feat also achieved by Glenn Snyders (North Shore), Sophia Batchelor (Christchurch) and Matt Stanley (Matamata).
Boyle clocked an outstanding 4m 5.67s to qualify top in the heats, more than four seconds inside the qualifying mark for the world championships.
She backed that up with a 4m 6.39s effort to win the final by more than four seconds from Wellington's Samantha Lucie-Smith, who set a new personal best.
Snyders, now based in southern California, impressed to clock 1m 00.14s in his heat of the men's 100m breaststroke, 0.7s inside the qualifying mark for the world championships.
The evening session began with two further qualifying performances when 17-year-old Batchelor went under the world championship mark in the 100m butterfly by the slimmest of margins, while London Olympian Stanley produced a classy swim to qualify in the 400m freestyle.
Paralympics star Sophie Pascoe had some good and bad news.
She unofficially broke the world record in the 50m breaststroke when she clocked 36.17s, but the electronic touchpad malfunctioned, so the record cannot be ratified.
