Iceberg seen of the coast of sub-antarctic Macquarie Island. Photo / Brett Quinton Expand

Iceberg seen of the coast of sub-antarctic Macquarie Island. Photo / Brett Quinton

A massive iceberg is likely to pass New Zealand shores now that it has entered the country's waters.

Niwa oceanographer Mike Williams said the iceberg was spotted near the sub-Antarctic islands about 500km from New Zealand.

Dr Williams has been tracking the iceberg, estimated to be 500m wide and 50m high, since it was spotted in the Southern Ocean.