Two photographers on their first foray after Covid-19 lockdown recorded a brilliant view of the Milky Way and a bioluminescence - "a fantastic surprise".
A bioluminescence is caused by a plankton bloom in the ocean as the plankton seeks to avoid predators.
Alistair Bain and Lawrence Yang made the night-time trip to Te Arai Beach, just south of Mangawhai, about an hour and a half north of Auckland on Northland's east coast.
Bain said he had seen bioluminescent algal blooms a few times in Whangaparāoa in north Auckland, but this was the first time he has seen one at Te Arai Beach.
A small group of astrophotographers also saw the display, but due to the remote location of the beach, and being night time, the two photographers said they were fairly sure they had the beach to themselves.
Bain said Te Arai was more rural than Whangaparāoa, which meant less light pollution from buildings and roads. A camera can see the stars more clearly because it does not have to compete with other ambient light.
However, being dark, the camera's auto-focus would not work and the photographers must manually focus the lens on a single star.
"The darkness makes the stars and glowing water look spectacular but that lack of light makes it very difficult to capture anything else in the photo like a person, the sand, or rocks to give the viewer some perspective of where you are."
Bain said the Milky Way was not visible in the New Zealand sky for some months, and a bioluminescence was not particularly common either.
"To be at a location facing the correct direction, at the right time, with no clouds or city lights is hard enough but to capture a picture of both the glowing waves and the Milky Way core is really special."
Marine scientist Daniel Ward said the glow in the water was caused by an oxidation reaction within the plankton organism's body to produce light so it could distract and evade predators.
He said it could be difficult to predict when the blooms of marine plankton would show up, even in their preferred warmer water temperatures.
"It is more common in warmer water, however the plankton's growth depends on more than just temperature, such as the salt levels in the water, so there is always the chance to see it any time of year."
Bain and some Hibiscus Coast residents photographed a stunning display of bioluminescence in Tindalls Bay, north of Auckland in January.