The Garmin Striker Cast is a postable castable fishfinder that turns your phone into a fishfinder. All you need do is install the Garmin Striker app which is available on both the Apple App Store and Google Playstore. From the app, you can setup the Striker Cast and you are good to go.
The Striker Cast comes with an inbuilt GPS that allows you to generate maps, and it will also show you the water temperature. It has a casting range of 200ft and a maximum scanning depth of 150ft.