A pond in Hawaii has mysteriously turned bright pink - with experts voicing concerns about the bizarre phenomenon.
Curious onlookers have been flocking to the pond after images first appeared on social media.
Volunteers at the Kealia Pond National Wildlife Refuge on Maui, some of whom have been around the water for 70 years, say they have never seen anything like it before.
Bret Wolfe, the refuge manager, said he was first alerted by someone walking on the beach who told him: "There's something weird going on over here".
But while it may look fun, officials think the cause of the pond turning pink could be more concerning.
Maui has been experiencing a drought which scientists say may be responsible.
Toxic algae was first considered a suspect, but lab tests found it was not the cause of the colour.
Instead, an organism called halobacteria might be the culprit.
Halobacteria are a type of archaea or single-celled organism that thrive in bodies of water with high levels of salt.
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The salinity inside the Kealia Pond outlet area is currently twice the salinity of seawater.
However, Mr Wolfe said the pond has previously been through periods of drought and high salinity and it remains a mystery why the colour has changed now.
DNA analysis still needs to be done to confirm the source of the transformation.
Visitors are being warned not to enter the water or eat any fish caught there while the cause is investigated.