Abstract: A buoy for marine vessels that is responsive to a transmitted RF signal of a set frequency consisting of an RF receiver disposed within the buoy and tuned to a set frequency of the transmitted RF signal and an antenna coupled to the input of the RF receiver. A switching circuit is coupled to the RF receiver, and a lamp is disposed on the buoy so that when the RF receiver receives a signal at the set frequency, it will operate said switching circuit and turn on said lamp. The buoy may be a pick-up buoy having an elongated stem on the top of the buoy, and containing the antenna. The lamp can also be mounted on the end of the antenna. A sound source coupled to the output of the switching circuit can sound an audible signal in response to the transmitted RF signal.