PWC Dashboard is designed to be run on a water-resistant phone mounted on your personal water craft (PWC). The app is free, has no ads, and has all features enabled.
It displays your speed (in miles per hour in the US, kilometers per hour elsewhere); your heading (N, NE, E, SE, etc.); a map of the body of water you're on, including your current location and your launch point; an arrow pointing towards your launch point (as the crow flies, i.e. if there are bodies of land between you and your launch point, the arrow can not guide you around them).
For the convenience of boaters in New Hampshire, there's an indicator showing how to navigate around red-topped and black-topped spar buoys.
Since this app is meant for a PWC, where the sun can shine directly on the screen and the user cannot generally fiddle with controls, the display is high contrast with large fonts, and shows all the important information at once.
The accompanying video demonstrates using the app.