this is showing tonite...
http://channel.nationalgeographic.com/episode/finding-atlantis-4982/Overview

found this pbs link...only to see that it is from 2008
http://www.pbs.org/wnet/secrets/episodes/sinking-atlantis/90/
http://www.pbs.org/wnet/secrets/transcripts/sinking-atlantis-transcript/91/

A tsunami was responsible for destroying this civilization 5,000 years ago.