Not a ditching per se, but a successful water landing nonetheless.

In 1978, a National Airlines 727 "landed" in Escambia Bay on final approach to PNS (Pensacola, FL). Visibility was poor and the pilots did not keep an eye on their altitude. By time they realized how low they were, it was too late. However, because the plane was level for landing, they made a relatively smooth landing. Everyone on board survived the landing, however three people died during the evacuation...drowning I believe.

http://www.airdisaster.com/photos/na193/photo.shtml