My favorite use of this app is actually for ice fishing. I fish in open water season and with my fish finder I look for structure (perch, bass, crappie) or sandy/soft sonar returns (lake trout, rainbow trout). I also use the Navionics to show me drop off areas/sharp contours. Then I mark these spots on my phone and when I return during hardwater season I know exactly where to go for the species I am targeting. Especially deep in the season when there can be 3' of ice to drill. It can waste a lot of time to drill a hole, then pull out the flasher to see what depth I might be in and what kind of structure there is on the bottom. Sometimes it's blowing snow, 20 below zero and you want to get that pop-up shanty and heater deployed as soon as possible. For that purpose Navionics is absolutely priceless.