New Zealand is one of the few countries in the world which makes their nautical charts available for free. Others include the USA, Brazil, and Argentina. Here’s a good listing of the worldwide nautical publishing agencies. And the USA is the only country which has placed in the public domain the tide and current harmonics needed by DeepZoom to create animated current displays.
Instead, each country has a semi-functional website where you can license charts and download them in a bewildering array of formats. Or you end up just paying your charting application to handle the licensing on your behalf.
Since this is a low budget operation, I can’t justify the rather exorbitant licensing cost for charts from each national government publishing entity. If DeepZoom ever grows up to play in the big leagues, it will need to face this issue.