Not only is the AT Pro an excellent land hunter, it should perform well in salt water as well as freshwater. I have accumulated most of my gold finds at or in fresh water bodies of water. The unique audio sounds of the AT Pro should be a real asset for pulling some decent finds from nearby lakes. Here are a couple of AT Pro videos to go over some fresh water detecting techniques.
http://www.garrett.com/hobbysite/hbby_at_pro_fresh_water.aspx
http://www.garrett.com/hobbysite/hbby_at_pro_fresh_water2.aspx
http://www.garrett.com/hobbysite/hbby_at_pro_fresh_water.aspx
http://www.garrett.com/hobbysite/hbby_at_pro_fresh_water2.aspx