Icebergs not as close as thought

A report of an iceberg floating near Stewart Island has proved to be premature.

On Tuesday morning Australian Antarctic Division glaciologist Neal Young - using satellite technology - said he had detected an iceberg floating just 30 kilometres off Stewart Island.

That news prompted Helicopters Otago to send to down a flight - which found that the iceberg was in fact an underwater reef.

Mr Young said satellite technology has its limits. He added that the cluster of icebergs known to be near Macquarie Island could still reach Stewart Island, but only if they survive breaking apart.

Helicopters Otago managing director Graeme Gale said the icebergs needed to come closer before he would begin scenic flights, but these could start as early as the weekend if the icebergs continued to move towards the mainland.

The cost of a seat on the helicopter was estimated at $600 because of the distance.

Mainland Air chief pilot Phil Kean said the company was just waiting for the position of the icebergs to be confirmed as strong northwest winds in recent days could have disrupted their progress.

A seat on a chartered sightseeing flight would cost $250.

Dr Young, a glaciologist with the Australian Antarctic Division Antarctic Climate and Ecosystem Co-operative Research Centre, said hundreds of icebergs, spread over a large area around Macquarie Island, were drifting towards New Zealand.

The icebergs had been travelling northeast with the current, but eddies or storms could still divert them away.

They had been carved from a larger iceberg that was perhaps 30sq km in area and originated from the Ross Ice Shelf nearly a decade ago.

The icebergs varied in size from 50m up to 2km in length, he said.

Numbers would increase as large icebergs split into smaller sections.

At the same time, smaller sections would disappear as they broke up further and melted.

Coastal navigation warnings were still in place to encourage shipping to watch out for the icebergs.

rebecca.fox@odt.co.nz