Owners of iPhones and other smart phones who fish can do a smart thing and download lake charts from Navionics (www.navionics.com). The charts are extremely detailed and, once downloaded, don't require a mobile signal to access. Paired with GPS, the application allows anglers and other boaters to navigate unfamiliar waters, showing in real time the boat's location and movement. Additionally, route tracking and planning are easy. Even if a boat is outfitted with a similar on-board unit with larger screen, the mobile application is a great backup.