A seabed-to-surface riser system is disclosed. The seabed-to-surface riser system has a group of subsea riser supports that each support riser pipes extending from the seabed to mid-water. Jumper pipes extend from there to a floating production, storage and offloading (FPSO) offset horizontally from the riser support in a flow direction. The group of riser supports is disposed to one side of the surface installation. Laterally-extending lines are attached to at least the outermost riser supports of the group. Those lines apply mutually-opposed stabilizing forces to those outermost riser supports in directions transverse to the flow direction.