VERTCRS["Instantaneous Water Level depth",
    VDATUM["Instantaneous Water Level"],
    CS[vertical,1],
        AXIS["depth (D)",down,
            LENGTHUNIT["metre",1]],
    USAGE[
        SCOPE["Hydrography, drilling, marine geophysics."],
        AREA["World."],
        BBOX[-90,-180,90,180]],
    ID["EPSG",5831]]