Navionics have just released a new upgrade for their boating app, and this one really is amazing.
After the introduction of Sonar Chat Shading this is a distinct improvement. It gives a much clearer view of the bottom structure.
Relief shading delivers highly detailed shading that combines colour and shadow to provide an easy-to-interpret, clearer view of bottom structure than contour lines alone.
If you want to see a demo then watch this video.