ONE News has pictures of iceberg chunks edging closer to the country's shores.
They have doubled in number in the past 24 hours and it is now believed there are 100 icebergs, with some at least 100 metres long.
Most have clustered 350 kilometres west of Macquarie Island and four smaller icebergs are already north of the Auckland Islands.
New Zealand has had icebergs like this before but never in these numbers, says NIWA's Mike Williams.
"Having 100 potentially coming this way is really interesting. It'll be interesting to see how many actually make it here," he says.
Three years ago just one iceberg set off a mini economic boom, with tourism operators making the most of it.
"This certainly appears to be bigger than the 2006 event. We'll see what happens as to whether they get too close to New Zealand," says Williams.
Scientists are still puzzled over why so many are heading north.
NIWA's research vessel the Tangaroa will set off from Wellington next week to investigate.
"This is a great way to check what the satellites are seeing, but also from a ship we can see how high (the icebergs) are and we can also see the small ones as well," Williams said.