Most of the data underlying the LINZ topographic maps of New Zealand is now available for free download as a public service provided by Koordinates Ltd:

Land Information New Zealand topographic data version 14

Certain LINZ topographic layers are only available after paying a small fee, generally because they’re very dense types of data. Two examples are the New Zealand 20m Contours and the New Zealand Spot Heights.

Many topographic layers covering the Chatham Islands are available from Ollivier & Co.

Ollivier & Co. have made their topographic image tiles available for purchase via Koordinates.

Topographic image (or raster) tiles are images designed to closely resemble the LINZ topographic map series, but continuous across New Zealand. There are no borders or other artifacts present at the boundaries of the map sheets.