Penguins at Kelly Tarlton's would hardly know they're in Auckland and not Antarctica, with staff extending the hours their enclosure is lit to match the summer solstice.
"It's replicating the natural environment they're from as best we can," says Madeline Seaman, team leader of the aquarium's penguin department.
Lighting in the enclosure is matched to the sub-Antarctic lighting cycle, so in summer the daylight hours are increased dramatically. For around two weeks, nights in the penguin enclosure will only get dark at 10pm, lightening up again at 1am.
Matching the day and night cycles to what the penguins would experience in the wild helps regulate their breeding and moulting cycles, Ms Seaman says.
She says it's more critical for the larger king penguins than the small gentoos.
For the king penguins, their breeding cycle and moult are based on their lighting changes between winter and summer.
"The day length for the kings is absolutely critical for keeping them all in sync with what should be happening in nature," Ms Seaman says.
The penguins will be able to enjoy the longer days for around two weeks before the keepers start gradually extending the nights again.