Summary Green’s functions in an unknown medium can be retrieved from single-sided reflection data by solving a multidimensional Marchenko equation. This methodology requires knowledge of the direct wavefield. The Marchenko equation is a powerful tool for retrieving Green’s functions, which are essential for subsurface imaging. By solving this equation, we can obtain the Green’s functions between virtual sources in the subsurface and receivers at the surface, enabling us to image the subsurface more accurately. This approach has the potential to revolutionize subsurface imaging and monitoring.