A mattress includes a generally rectangular prismatic foam body, having a length, a width, and a thickness, having a top surface, a plurality of slits in the top surface of the foam body extending across the width of the body to divide the top surface into a plurality of adjacent slats. An elongate chamber extends through the body, parallel to and aligned with each slit. At least one fluid filled cell disposed in each of the elongate chambers to support the edges of adjacent slats.