Navionics offers a free Boating app download for Apple and Android. The free app download includes basic features and a two-week free trial of Charts and Advanced Features.
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 have access to Charts and Advanced Features, you can purchase a one-year subscription for your desired region from within the app by going to Menu > Charts & Upgrades.
With the purchase of a subscription package from within the free app you get:
Chart Updates - including our official Nautical Chart data, as well as SonarChart™, our high-definition bathymetric mapping for selected areas of the world. See the coverage map on our SonarChart page - http://www.navionics.com/sonarcharts. You also have access to Navionics Community Edits and the Garmin ActiveCaptain Community for tons of local knowledge details.
Advanced Features - Navigation Module, Dock-to-dock Autorouting, AIS display, Track Timeline, Advanced Map Options, import/export GPX files, Plotter Sync, and Weather Data.
Once your subscription has expired you can continue to get:
The ability to download charts (Nautical and SonarChart) 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.