Panel suitable for assembling a waterproof floor or wall covering by interconnecting a plurality of said panels with each other, wherein the panel has a substantially planar top surface, and a substantially planar bottom surface, at least four substantially linear side edges comprising at least one pair of opposite side edges which are provided with interconnecting coupling means for interconnecting one panel within another, the panel having a sandwich structure which comprises a central layer basically composed of a thermoplastic material, a rigid top layer and a rigid bottom layer.