Earlier Boyle had finished fourth in the final of the 200m freestyle in 1:59.24, won by last year's overall World Cup winner Katinka Hosszu from Hungary and Italy's former world champion Federica Pellegrini.
Masterton's Isaac Foote was the only other New Zealand swimmer to qualify for a final on the first day of the two-day meet, finishing eighth in the 200m butterfly in 2:00.27.
Day 1 NZ Results:
Women 200m freestyle: Katinka Hosszu (HUN) 1:55.41, Federica Pellegrini (ITA) 1:57.42, 2; Jaz Carlin (GBR) 1:58.45, 3. Also: Lauren Boyle (NZL) 1:59.24, 4.
Women 800m freestyle: Lauren Boyle (NZL) 8:25.96, 1; Jaz Carlin (GBR) 8:30.79, 2; Sarah Koehler (GER) 8:35.16, 3.
Men 200m butterfly: Viktor Bromer (DEN) 1:55.98, 1; Chad Le Clos (RSA) 1:56.03, 2; Zheng Quah (SIN) 1:56.26, 3. Also: Isaac Foote (NZL) 2:00.27, 8.
CAPTION: Lauren Boyle in action (Credit: Ian Macnicol)