Researchers who live on Macquarie Island, a sub-Antarctic island in the Pacific Ocean where millions of seals, sealions, penguins and seabirds roam free, are used to some pretty amazing sights.

However scientists on the World Heritage listed island were left in awe last week as a gigantic iceberg floated past their station, which sits half way between Australia and Antarctica.

"I've never seen anything like it. We looked out to the horizon and just saw this huge floating island of ice," said Dr Dean Miller, a fur seal biologist who was the first to spot the iceberg about 8km (5 miles) off the north west of Macquarie Island.

Scientists at the Australian Antarctic Division (AAD), which published photos and an account of the iceberg on its website, estimated the giant block of ice was about 50m (165ft) high and 500m (1650ft) long.

An AAD glaciologist, Neal Young, said that it was unusual for such a large iceberg to be seen so far north.

“The iceberg is likely to be part of one of the big ones that calved from the Ross Ice Shelf (in Antarctica) nearly a decade ago,” Dr Young wrote on the AAD website .

“Throughout the year several icebergs have been drifting slowly northwards with the ocean current towards Macquarie Island. We know there are also a few more icebergs 100-200km west of the island.”

The AAD, which runs a research station on the island, said the giant block, which was floating towards New Zealand, was most likely to break up and melt rapidly as it moved further north.

Dr Young said that once the iceberg begins to break up over the coming months it could become hazardous for shipping.

The extremely remote Macquarie Island, which lies in the southwest of the Pacific about 1500km (930 miles) southeast of Tasmania, is officially listed as a World Heritage Area because of its incredible populations of marine and plant life.

The island – a Tasmanian state reserve maintained by the AAD - is approximately 34km long and 5.5km wide at its broadest point.

About 3.5 million seabirds and 80,000 elephant seals arrive on Macquarie Island each year to breed. Recently fur seals have begun to re-establish their populations on the island after almost becoming extinct in the early 19th century.

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