Navionics offers a free Boating app download for Apple and Android. The free app download includes basic features and a free trial period of Charts and Advanced Features for your desired region.
After your free trial period you will have access to base mapping only. Basic features are also still included. See Free Boating App Options. If you would like to continue access to Charts and Advanced Features, you can purchase a one-year subscription for your desired region from within the app.
With the purchase of a subscription package from within the free app you get:
Chart Updates - including SonarChart™, our high-definition bathymetric mapping for selected areas of the World. See the coverage map at the bottom of our SonarChart page - http://www.navionics.com/sonarcharts
Advanced Features - Navigation Module, Dock-to-dock Autorouting, Timeline, Advanced Map Options, Plotter Sync and Weather Data - are available free with a subscription.
Once your subscription has expired within an app with a region purchased you can continue to get:
The ability to download charts (Nautical and SonarCharts™) within your coverage area without the benefit of updates. All previously downloaded charts are still accessible.
Basic app features; see Free Boating App Options for a full listing