The foghorn (also called nautophone, although I have always called it fog lighthouse) of Cape Estay, in Vigo (Galicia, Spain), sounding on September 29, 2017. This nautophone (is the device that it is seen to the left) is the only one of the Vigo Estuary (of which I have knowledge), and is property of the Port Authority of Vigo. It is located next to the Cape Estay lighthouse (we see it in the video, on the right). The acoustic signals of the foghorn serve to alert the boats of the presence of the coast on thick foggy days.
Years ago there was another nautophone in the old lighthouse of Cape Silleiro, at the southern end of the Ría de Vigo. It was installed in the place that once occupied the lighthouse tower.