Heat Flow Maps show color-coded contours of the global distribution of heat flow at the surface of the Earth's crust. The estimates are based on empirically determined characteristic values for the heat flux in various geological and tectonic settings. Observations of the oceanic heat flux have been corrected for heat loss by hydrothermal circulation through the oceanic crust. The global data set so assembled was then subjected to a spherical harmonic analysis. The global heat flow map is a representation of the heat flow to spherical harmonic degree and order 12.