There are numerous apps for off road nav, I have an iPad app (I use aniPad with a 'Ram Mount' for nav) called "MotionX GPS". You can choose between several topo maps&/or use satellite photo navigation (I use satellite a lot), these can be downloaded so that you can use them without a cell signal. There's also "PDF Maps", "Ovital", "Trail Explorer", "EveryTrail", "View Ranger", "Terrain Navigator Pro" & a host of others. Some are "free" but the're a bit limited in what you can do, most charge a small fee.