Hydrographic survey mapping the seafloor in the Bay of Plenty has begun, with the data contributing to safer navigation in approaches to ports and wharves.

Toitū Te Whenua Land Information New Zealand (LINZ) is responsible for surveying the waters around New Zealand and updating nautical charts to help keep people safe at sea.

Senior hydrographic surveyor Annette Wilkinson said the work in the Bay of Plenty would take place in two parts by contractors, DML Surveys.

The MV Tranquil Image, has been charting back and forth offshore Tauranga and Whakatāne.

People may notice this survey boat, which can survey 24 hours a day.”

The survey uses multi-beam echosounders mounted on the boat that slowly criss-cross an area to build detailed 3D images of the seafloor. Three-dimensional pictures show up objects on the seafloor such as shipwrecks and undersea mounds.

“The survey will investigate a number of wrecks, rocks, and other natural features on the seafloor that pose a threat to navigation, Ms Wilkinson said.

“A smaller vessel, the Tupaia, will be mapping the shallower waters of Ōpōtiki in early 2025.

“Every area of New Zealand waters we survey updates nautical charts to help ensure Kiwis, shipping companies and other mariners have the latest information to safely navigate our waters,” she said.

Three-dimensional models of the data collected will be freely available on the LINZ Data Service once it is processed next year.

This will complement other bathymetric (shape of the seafloor) data collected in the Bay of Plenty, including coastal zone data from a technical trial earlier this year.

“The survey is filling in data gaps, contributing to a higher-definition picture of the areas we know mariners are navigating.”

The data can also be used for a range of scientific research projects, including tsunami modelling and marine resource management.

“This data will also help us understand the shape and type of the seafloor, which is really useful for researchers and planners,” Ms Wilkinson said.

Updated nautical charts will be available from the free NZ Electronic Navigational Chart Service.