An expert on sub-Antarctic New Zealand says it is possible that the four icebergs sighted off the Auckland Islands might reach New Zealand intact, although they are showing signs of deteriorating.

The largest of the icebergs is 80 metres long and only 10 percent of its total size is above the water line.

Rodney Ross, an expedition leader from the tourist ship Spirit of Enderby says the icebergs appear to be moving north at the rate of about 1.25 kilometres an hour.

?We first sighted them 10 miles off the eastern entrance to Carnley Harbour in the Auckland Islands. Weather and sea conditions at the time prevented a closer inspection but weather conditions improved today and we were able to locate them and sail close by."

The Spirit of Enderby left the Auckland Islands on Wednesday bound for Macquarie Island and expects to encounter more icebergs.

Mr Ross says the crew are on special 'iceberg lookout' as they pose a significant risk to shipping. He says icebergs have never been an issue in the sub-Antarctic islands before but that may change.