How can Antarctic icebergs reach waters near New Zealand?

Antarctic icebergs reach waters near New Zealand primarily by entering the Antarctic Circumpolar Current, also known as the West Wind Drift.

After calving from the Antarctic coast, icebergs typically move westward within the Antarctic Coastal Current. If they break away from this current, they enter the eastward-flowing Antarctic Circumpolar Current, which circles the globe at latitudes between 40° and 60° S. Once in this system, icebergs are driven eastward by both the current and the wind. Simultaneously, the Coriolis force pushes them in a northeasterly direction, allowing them to drift into lower latitudes and warmer waters.

This mechanism can bring icebergs near New Zealand; for example, a chain of icebergs was observed off the coast of Dunedin on New Zealand’s South Island in November 2006. Under extreme conditions, such as being captured by a cold eddy, icebergs may reach even lower latitudes before they eventually disintegrate.1