They were matched by the Para-Swimmers with six meeting the qualifying standard in eight swims for the IPC World Championships to be staged in Glasgow in July.
The brilliant Sophie Pascoe led the way with two qualifying times and a world record, joined by Halberg Award winner Mary Fisher, with two qualifying times, and Jesse Reynolds, Hamish McLean, Rebecca Dubber and Nikita Howarth.
Snyders booked a place to Kazan a decade after his first visit to the world championships, in his signature event, the 100m breaststroke.
The 28-year-old, now based in Los Angeles, clocked 1:00.35 to sneak under the qualifying time for the world championships by 0.1s.
He set the 14th-fastest time this year but felt nervous after a challenging morning swim when his goggles filled with water from his dive.
He finished clear of Julian Layton (Greendale) 1:02.64 and Alex Peach (United) 1:02.91.
Australian-based Stanley also qualified when he went 3:50.73 in the 400m freestyle, which was 15/100ths of a second under the world championships mark.
The race was won by New Zealand-based Michael Dai from China in 3:50.64, although the London Olympic representative has yet to qualify to swim for this country.
He dragged Stanley through under the qualifying time with Wharenui's Matthew Hutchins, currently swimming at the University of Wisconsin, third in 3:50.93, only 6/100ths of a second outside the qualifying mark.
"I've had a limited build up so I knew I would not be at my best and that was pretty hard for sure," Stanley said.
Commonwealth Games champion Boyle was timed at 4:06.13 to win the 400m freestyle, the ninth-fastest time in the world this year. This gives her three of the world's top-10 times this year. "With a great swim in Australia last week and now two good 4:06 swims today that is pretty satisfying at this stage," Boyle said.
The championships continue until Friday.
Day 1 Results:
Men 100m breaststroke: Glenn Snyders (North Shore) 1:00.35, 1 (Qualified FINA World Championships); Julian Layton (Greendale) 1:02.64, 2; Alex Peach (United) 1:02.91, 3.
Women 100m butterfly: Helena Gasson (Fairfield) 1:00.40, 1; Samantha Lee (Capital) 1:00.58, 2; Georgia Marris (United) 1:00.98, 3.
Men 400m freestyle: Michael Dai (Coast) 3:50.64, 1; Matthew Stanley (Matamata) 3:50.73, 2 (Qualified FINA World Championships); Matthew Hutchins (Wharenui) 3:50.93, 3.
Women 400m freestyle: Lauren Boyle (United) 4:06.13, 1; Emma Robinson (Capital) 4:11.32, 2 (Qualified FINA World Championships); Monique King (North Shore) 4:19.62, 3.
Men 50m butterfly: Nielson Varoy (Parnell) 24.44, 1; Daniel Hunter (Howick Pakuranga) 24.58, 2; William Benson (Heretaunga Sundevils) 24.76, 3.
Women 50m backstroke: Gabrielle Fa'amausili (Roskill) 28.43, 1; Bobbi Gichard (Greendale) 28.99, 2; Caroline Baddock (North Shore) 29.88, 3.
Men 100m backstroke: Corey Main (Howick Pakuranga) 54.41, 1 (Qualified FINA World Championships); Daniel Blackborrow (Visitor, MLC Aquatic) 56.76, 2; Corneille Coetzee (North Shore) 56.83, 2; Andrew Trembath (Neptune) 57.63, 3.
Women 100m breaststroke: Natasha Lloyd (North Canterbury) 1:09.96, 1; Kendall Reidy (Central Hawkes Bay) 1:12.81, 2; Jane Ip (West Auckland) 1:13.04, 3.
Men 200m individual medley: Bradlee Ashby (Fairfield) 2:00.76, 1 (Qualified FINA World Championships); Mitchell Donaldson (North Shore) 2:04.40, 2; Wilrich Coetzee (North Shore) 2:05.09, 3.
Women 200m individual medley: Helena Gasson (Fairfield) 2:17.45, 1; Kate Godfrey (Neptune) 2:18.21, 2; Yeonsu Lee (North Shore) 2:21.27, 3.
Para Swimmers:
Men 100m breaststroke: Christopher Arbuthnott (Ice Breaker) 1:20.21, 1; Tama Solouota (Papatoetoe) 1:41.61, 2; David Beck (West Auckland) 1:39.12, 3.
Women 100m butterfly: Sophie Pascoe (QEII) 1:03.72, 1 (Qualified IPC Swimming World Championships, World Record); Bryall McPherson (North Shore) 1:33.84), 2.
Men 400m freestyle: Jesse Reynolds (Fairfield) 4:30.15, 1 (Qualified IPC Swimming World Championships); Hamish McLean (Wanaka) 5:43.63, 2 (Qualified IPC Swimming World Championships).
Women 400m freestyle: Mary Fisher (Capital) 5:26.72, 1 (Qualified IPC Swimming World Championships); Rebecca Dubber (North Shore) 5:33.72, 2 (Qualified IPC Swimming World Championships); Tayla Clement (North Shore) 5:26.38, 3.
Men 50m butterfly: Daniel Gaualofa (Bay of Islands) 30.41, 1; David Beck (West Auckland) 34.98, 2.
Men 100m backstroke: Jesse Reynolds (Fairfield) 1:08.12, 1; Christopher Arbuthnott (Ice Breaker) 1:13.22, 2; Tama Solouota 1:27.47, 3.
Women 100m breaststroke: Georgia Gray (North Shore) 1:27.72, 1; Nikita Howarth (Te Awamutu) 1:31.06, 2.
Men 200m individual medley: Christopher Arbuthnott (Ice Breaker) 2:33.62, 1; Hamish McLean (Wanaka) 3:14.65, 2; Daniel Gaualofa (Bay of Islands) 2:42.25, 3.
Women 200m individual medley: Sophie Pascoe (QEII) 2:26.93, 1 (Qualified IPC Swimming World Championships); Nikita Howarth (Te Awamutu) 3:02.66, 2 (Qualified IPC Swimming World Championships); Mary Fisher (Capital) 3:01.56, 3 (Qualified IPC Swimming World Championships).
Caption: Corey Main celebrates his qualifying effort in the 100m backstroke while Glenn Snyders focusses on the start in his qualifying swim in the 100m breaststroke on the first day of the New Zealand Open Championships in Henderson.
