The town of Oia is located in a straight coast, similar to the Portuguese coast, and different from the rest of the Galician coast to the north. In this town, we find the Monastery of Oia, close to the sea, which has witnessed many battles to defend the town against the pirates’ attack. The quietness in this place is different from that of the thick inland forests. There, the waves crash against the rocks, especially in windy winter days. This place may have been chosen by the monks as the opposite to calmness; as a metaphor of God’s fury against sin, symbolised by the giant waves.
According to some references, the Monastery of Oia was founded in the early 10th century. However, it is not clear if there were monks living there at the time of Martiño de Dumio, in the 6th century. Over the years, the domains of the monastery extended along the coast, to the town of the same name, Oia, and the regions of Vigo, O Condado, O Morrazo and O Baixo Miño.
The periods of economic growth were followed by periods of decadence, as a consequence of a decline in trade and the wars against Portugal, in the 17th century, the poor harvest and mismanagement of some abbots, especially at the end of the 18th century and the beginning of the 19th century, shortly before the Spanish confiscation and expelling of the monks from the monastery.
In the beginning of the 20th century, at the end of the Portuguese monarchy and after having expelled the Portuguese Jesuit monks, the monastery became their residence (but not as their property, but paying a rent), and they founded a school, similar to those previously opened in the towns of Pontevedra, Santiago de Compostela and Verín. During the Second Spanish Republic, the government decided that the Jesuits did not meet the conditions to comply with the Constitution, since they vowed obedience to the pope, and they were expelled and thus the school was closed.
In the inside of the church the ribbed vaults, which are richly decorated with filigree, stand out. The central nave is made of pointed arches and the severy is hidden under a lime layer.
One of the monastery's cloisters is a masterpiece of stonework, with semi-circular arches leading to the central courtyard and ribbed vaults that start from elegant corbels. A second cloister is known as the "outside" cloister because it is barely enclosed by an uncovered wall. Moreover, what used to be the courtyard now is covered with weeds. The appearance of its walls has changed, as their openings do not follow any pattern.
Today the monastery and its premises belong to private owners. Several projects have been considered to open a business in its facilities, but so far none of them has been successful.
The Monastery of Santa María de Oia was declared National Monument by decree on 3 June 1931.