Unusually warm waters and stable seas are creating prime conditions for stunning displays of bioluminescence along Auckland's coast.
Amateur photographers have been flocking to Whangaparaoa Peninsula to capture the spectacle.
Simon Thrush, a professor of marine sciences at Auckland University, said a number of plants and animals could be responsible for the spectacle.
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Professor Thrush said the creatures light up for a range of different reasons including communication between organisms or a response to predators.
"I don't think there is anything unusual about what's going on. Often these things vary from year to year, just depending on climatic conditions.
"This year the waters are a little bit warmer so we might be seeing a stronger response because of that," he said.
The displays don't necessarily mean there are any problems happening in the waters, he added.
"If we've got a big storm going then we just aren't going to notice much [bioluminescence] because the effect of the storm both affects the water column and breaks up the surface."