An open water marine barrier system is provided. Embodiments include a marine barrier with two elongate buoyant members, an elongate net support member between the two buoyant members and above the buoyant members, and an elongate lower ballast member between the two buoyant members and below the buoyant members. Stanchions extend between the members to support them and maintain the spacing between them. An impact net is attached to the net support member and a stanchion extending between the two buoyant members. When a moving vessel impacts the impact net, the net deflects to transfer a force of the impact to the net support member, the stanchions, and the buoyant members, which engage the water to transfer the impact force to the water and arrest the motion of the vessel. The ballast member provides a force to restore the barrier to an upright position when the barrier rotates from vertical.