A measurement system for determining a density ρ or a compressibility κ of a liquid medium in a vessel includes: at least one pressure sensor for measuring a hydrostatic pressure Δp of the liquid medium as a measured hydrostatic pressure Δp; at least one ultrasound sensor for measuring a first time of flight t1 along a first propagation path comprising a point at a level surface of the liquid medium, and for measuring a second time of flight t2 along a second propagation path, which is different from the first propagation path; and a control unit for determining the density ρ or the compressibility κ of the liquid medium based on the measured hydrostatic pressure Δp, the first time of flight t1, and the second time of flight t2.