Tsunami

Source of the photo
http://www.monstrous.com/apocalypse/top_20_natural_disasters_photos.html
Author of the description
Gruiz Katalin

Tsunami.

You can find more photos about the Sumatra tsunami of  6th December, 2004 on the website of http://www.usc.edu/dept/tsunamis/2005/tsunamis/041226_indianOcean/sumatra/sumatra.html.