Abstract: A water mattress bag (1) of a watertight resilient material with tensile strength is provided with a valve for filling/draining water and is intended for use together with a main mattress member (3) of a resilient, flexible foamed plastic or the like, which is provided with a recess (4) in its upper face extending over a substantial portion of its length (L) and width (B). The bottom (1a) of the bag (1) is shaped with a bulge (1a') for cooperation with recess (4), and the top (1d) of the bag (1) has a length and width approximately equal to the length (L) and width (B).Water mattress (10) comprises the above mentioned components and a flexible sheet (15) on top of water mattress bag (1) and a mattress cover (16). Water mattress bag (1) is partly filled with water and extends outwards to the lateral edges (3a) of main mattress member (3) and covers the flat edges (3b) of main mattress member (3) around recess (4).

Abstract: A water bed mattress made of a water proof, flexible material that has tensile strength, comprising at least three chambers provided with valves, one chamber being divided into an upper and a lower chamber portion, said lower chamber portion being filled with water and particulate buoyancy material, e.g. polystyrene particles that are immersed in water, and said upper chamber portion being filled with water. The other chambers are filled with air and comprise air chambers provided at each longitudinal side of said mattress for stiffening its lateral edges, and adjustment chambers provided at the bottom of said mattress and provided with a common valve for adjustment of the pressure in said water bed mattress. Furthermore, central chambers are provided at the bottom of said mattress between said adjustment chambers.