You can actually cycle through 3 modes but which affect only the sea covered areas:
a) depth relief + sonar conditions - (ice info off)
b) depth relief - (sonar condit. off) + ice info in %
c) (depth relief off) - (sonar condit. off) + ice info sat view
C. should be what you are searching for. If there is no ice you have just 'flat-deep' blue.