Hazy conditions and a sulphury smell in the Bay of Plenty is being explained by a phenomenon called volcanic fog.
GeoNet said increases in gas emissions from Whakaari/White Island have combined with a developing sea fog in the Bay of Plenty to create a phenomenon known as "vog" or volcanic fog.
In a social media post, GeoNet said: "Vog is created when the sulphur-based volcanic gases mix with atmospheric moisture to form an aerosol.
"The light northerly winds are driving this onshore, there has not been an eruption to produce this.