The mapping of more than 3500 square kilometres of Northland seabed has been completed.
It is the biggest mapping exercise ever undertaken in New Zealand.
Land Information New Zealand says the project has revealed reefs and new information about the "Hole in the Rock" in the Bay of Islands and the wreck of the former HMNZS Canterbury.
The second phase of the project is biodiversity sampling. The agency says the coast is under pressure from aquaculture, tourism and landbased activities, and needs to be better managed.
