A boat has sunk off the coast of the Bay of Islands, just north of Waitangi, and two people are missing.

A spokesperson for Coastguard said a third person on board made their own way to shore.

Volunteers from Bay of Islands Coastguard have been at the scene since 7am and air support is on standby.

A local said search and rescue crews are combing the coastline near the Brampton reef.

The rescue comes less than two weeks after a large scale search and rescue exercise in the same area.

The exercise involved the premise that a cruise ship carrying 50 people had struck the reef and five people were dead.

The exercise involed search and rescue volunteers, Coastguard, Surf Life Saving New Zealand, the Red Cross and the Rescue Coordination Centre.