LINZ Data Service (LDS) Item Page - https://data.linz.govt.nz/layer/105085-nz-coastline-mean-high-water/

Purpose
The NZ Coastline – Mean High Water dataset is the first step towards improving the national coastline data for New Zealand. LINZ is currently working on a long-term project, “Coastal Mapping” to capture a range of national coastlines derived from LiDAR and bathymetry. This will enable us to generate coastlines, for example, for Mean High Water Springs, Chart Datum and Highest Astronomical Tide. The project is currently focused on capturing LiDAR and bathymetry data, and the timeframe for delivering the new coastlines will be established once the data capture has progressed.

Status
This dataset was created from LINZ Hydrographic and Topographic sources in August 2020 and will not be maintained in this form. This dataset will be replaced by a more accurate dataset in the future once data becomes available through the Coastal Mapping project.

Data sources and preparation
The spatial coastline data (1:50,000 scale) is sourced from the Topo50 series where it is described as a line forming the boundary between the land and sea, defined by mean high water. The source polygon data has been broken up into line segments to enable a coastal classification to be attributed to each segment of coast. Coastal classification data is based on official Electronic Navigational Charts published by the New Zealand Hydrographic Authority. Not all segments have been assigned a coastal category.