The main axis of the state is the Rhine river , that forms the border with Baden-W Ã 1\/4 rttemberg and Hesse in the southeast before running across the northern part of Rhineland-Palatinate . The largest river in the state is the Rhine , which forms the border with Baden-W Ã 1\/4 rttemberg and Hesse in the southeast before flowing through the northern part of Rhineland-Palatinate .