There is a marine gps app that covers la, ms, & al waters on the gulf called Flytomaps. It's only $6 and let's you mark unlimited waypoints. It uses noaa maps so I know that side is good b/c those are the maps I use when mapping out spots to fish. This would not be ideal for anything offshore. I think I may get it for my Cat Island trips were I still get good cell coverage. For instance, I've got a trip to Cat in mind where I stop at the gene Taylor reef, handkerchief shoal, and then pelican key on the way out there. I can find all those without a gps but it would make it 10x easier. Says the app gives distance and speed traveling in real time. For dinking and dunking close to shore, this could be cool.