This is a topographical map with included bathymetry (underwater topography).

I got the data from here:
https://visibleearth.nasa.gov/view.php?id=73963
https://visibleearth.nasa.gov/view.php?id=73934

I reduced the number of points to 2%, then used openScad to lay them on top of each other:

difference(){scale([.6, .6, .1])surface(file = "gebco_08_rev_bath_2.png", center = true);color("blue", 1.0)cube(size =[300, 300, 3], center=true);}translate([0, 0, 9.5])difference(){scale([.6, .6, .1])surface(file = "gebco_08_rev_elev_2.png", center = true);color("blue", 1.0)cube(size =[300, 300, .3], center=true);}