IT looks like a special effect from a Hollywood blockbuster - but this time it's real.

Tourists have captured rare footage of the moment a small iceberg from the Upsala Glacier, in Argentina, flips over.

As the watching crowd chatters excitedly, the bottom half of the iceberg emerges slowly from the ocean, sending a torrent of water rushing down its side.

The footage was posted on YouTube earlier this week, and has already been viewed more than 25,000 times.

Watch the video above.