Maps of the continuum intensity of the sunspots analyzed in this study. Panels A and B: sunspot simulations by Rempel (2012, 2015), panel C: NOAA AR 10923 observed by Hinode SOT/SP on 14 November 2006. The blue and green contours indicate the outer and inner penumbral boundaries (defined as 30% and 90% of the continuum intensity level of the quiet Sun, after smoothing the continuum images with a 2D Gaussian with σ = 812 km). The red boxes outline the regions that we used for deriving the Wilson depression in the two MHD simulations. We computed the Wilson depression across the entire FOV for AR 10923.