MultiTide is designed to help you plan for anything from a trip to your local tidal pool to a multiday kayaking trip. A network connection is only required to display the map data in the Local Stations view.
MultiTide for iPhone
http://itunes.apple.com/us/app/multitide/id384924457?mt=8&ign-mpt=uo%3D4%2522%2520target%253D%2522itunes_store%2522