Head to West Quay in Napier and you might see the water light up a shade of pink.
On Monday, the water around West Quay was a shade of bright pink, noticeable at the far southern end of the bar strip.
Hawke's Bay Regional Council team leader marine and coasts Anna Madarasz-Smith said the discolouration was an algal bloom.
"It's common to Hawke's Bay after periods of rain followed by warm temperatures.
"Algal blooms are a natural occurrence and provide a source of food into the ocean. While they are natural events, they can be increased by land based inputs.