Abstract: A barrier for protecting a port, waterway, or off-shore structure is provided. The barrier has a front elongated pontoon which extends substantially the length of the barrier. A net assembly, provided either in sections, or as an elongated net, extends vertically upward from the front elongated pontoon and along the length of the front elongated pontoon. The net assembly is affixed to the front elongated pontoon with one or more net support beams. The front elongated pontoon is supported by a rear pontoon support structure, which may be a series of pontoons, each connected to the front elongated pontoon and spaced apart the length of the front elongated pontoon, or an elongated cylindrically shaped rear pontoon which extends substantially the length of the barrier. In some embodiments, a rear net section is attached to the rear pontoon support structure. In another embodiment of the invention, a barrier system for protecting a port, waterway, or off-shore structure is provided.