Visualisation is pivotal for Science.
Unscientific colourmaps like the rainbow (a.k.a. jet) colour map distort, hide, and falsify the underlying data, while often making the figure unreadable to colour-blind readers or when printed in black and white (see #endrainbow).
Scientific colour maps, like the colour maps devon, davos, oslo, and broc, are perceptually uniform, perceptually ordered, readable as B&W print and colour-vision-deficiency (CVD) friendly. These and a few more scientific colour-maps can be downloaded and used freely below.
For MatLab, Python, R, GMT, QGIS, Plotly, Paraview, VisIt, Mathematica, Gnuplot, Surfer, d3, ImageJ, Fiji, Petrel, SKUA-GOCAD, GIMP, Inkscape, etc.