The alert comes after a 7.7 earthquake near New Caledonia, triggering a message for parts of the Far North and eastern coast of the North Island.
Affected areas include Ahipara and around the top of the country to Bay of Islands, Great Barrier Island, and Matata to Tolaga Bay on the East Coast.
Coastguard spokesperson Mike Buddle says they're monitoring the situation with Civil Defence, broadcasting the latest advice through all marine channels.
He says there may be surges that affect small boats and watercraft, and volunteers are on standby.
