Any of a number of alpine lakes in the mountains would be frozen over in the winter. If I had to choose one, I'd plump for Lochnagar in the upper Shotover. because it is at high altitude, and in a generally 'clear air' region.
Other candidates would be ones such as Lake Onslow in the mountains near Roxburgh, or Lake Alta on the Remarkables Ski Field.
The Crater lake in Mt Ruapehu would not make the list because it very much has thermal heating from its dormant volcano.
Read more: http://wiki.answers.com/What_is_the_coldest_lake_in_new_zealand#ixzz1LVvEYC9U
Lake Grassmere
Lake Taupo in the North Island
Lake Rotorangi
Lake Taupo, in the middle of the north island.
I don't know the answer, but I'd think Lake Te Anau would be in the top three, with its large fiord-like arms.
Lake Superior
Kiwi
According to Wikipedia, the deepest lake in New Zealand is Lake Hauroko in Fiordland National Park at the south end of the South Island, 463 meters deep (1,519 feet).
New Zealands biggest rock is a beach rock they can be as big as a big big super big mountin
The Waikato is the longest river in New Zealand, running for 425 kilometres through the North Island. It rises in the eastern slopes of Mount Ruapehu, joining the Tongoriro river system and emptying into Lake Taupo (New Zealands Largest Lake).
the rifleman
kiwi