Tourists in Iceland were admiring a glacier when a massive chunk of it collapsed into the water right before their eyes.
The break triggered a huge wave that came rushing their way, prompting them to run away in fear.
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The owner of an Icelandic tour company captured the whole thing on camera.
He said he could hear the crackling from the far-off glacier, which is a sign of calving.
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Calving is when a large section of a glacier breaks off. It's usually caused by the glacier expanding.
None of the tourists were hurt.