And you can also check the web of San Miguel de Aguayo's city hall (www.sanmigueldeaguayo.com)
About the Aguayo origin there are two posibilities. First, the legend, which says that a man saved the Spanish King Don Pelayo when he fought against muslims and who said: "Gracias a tí no temo al agua yo" ("Thanks to you I am not afraid of water" but written in old spanish). The second, and maybe the correct is that Aguayo means "abundance of water" and is a place name since the villages in Cantabria are rounded by water.
By the way, I am Juan Pedro Aguayo, from Madrid (Spain)