The Tasman Glacier, Aoraki Mt Cook National Park, is New Zealand’s largest glacier both in length and in width. 22,000-16,000 years ago, it was joined by nearby Murchison, Hooker, and Mueller glaciers to create a mega glacier of 115km. The giant glacier is actually the source of the popular Lake Pukaki, which was carved over thousands of years of receding ice.
Interesting fact about New Zealand: During the Ice Age, sea levels around the country dropped suddenly. Water became locked in glaciers, exposing surrounding sea floors. New Zealand became a single large island as the Cook Strait dried out. Even Stewart Island was connected to the mainland. Essentially, New Zealand was a giant glacier!