The earliest stone tools found on the Ons Archipelago are from the Paleolithic Period (which are kept in the Provincial Museum of Pontevedra), but the earliest settlements found date back to the Bronze Age.
The castro (fortified pre-Roman settlement) found in Canexol (Castelo dos Mouros) has yet to be excavated and still retains its circular defensive structure. To the north of the island, there’s another castro (A Cova da Loba), which is smaller in size. The earliest of the castros was Romanised around the 1st century, although hardly any remains from that period have been found (the lack of archaeological excavations makes it impossible to find a record). The Romans gave Ons Island the name “insula Aunios”, as mentioned by Pliny the Elder in his description of the Iberian Peninsula.
But until the Middle Ages, the Ons Archipelago was never mentioned very often. In 899, a reference to it was made, after King Alfonso III donated the island to the Diocese of Santiago de Compostela, with the Cabildo having possession of it until the 16th century. The presence of an anthropomorphic tomb (Laxe dos Cregos) in Area dos Cans makes it look like a convent or a shrine once existed; according to tradition, this tomb—which can be seen at low tide—is that of a monk who lived on the island.
In the 16th century, the Ons Archipelago changed hands and went on to belong to a family of nobles, the Montenegro family. At the end of the century, attacks by English privateers and pirates—led by Francis Drake—began, ending with the islanders fleeing to the coast. During the Peninsular War (Spanish: Guerra de la Independencia), two batteries were built—Castelo das Rodas (in the north) and the fort of Pereiró (in the south)—, but little remains of these, as the stone was used to build new houses. The opening of the Valladares fish salting factory (known as O Almacén) definitely became a draw for people from Bueu and Cangas to go to Ons Island; they eventually made fishing their main source of livelihood.
In the 1920s, the islands were repopulated with pine trees so the wood could be used for shipbuilding. In 1929, Manuel Riobó bought the Ons Archipelago and made use of the fish salting factory to build a conger eel and octopus drying plant and to begin marketing them. His heir committed suicide because of his Republican ideals at the beginning of the Civil War, leaving Ons Island without direct management. The Franco government—in the name of national defence—expropriated the islands in 1940 with the intention of building a submarine base, which would never be built. The war was followed by famine, which was further exacerbated by the island’s geographical and socio-economic situation; nevertheless, the population did not stop growing (in 1955, Ons had 530 inhabitants registered). It was during this period that schools and a church were built on the island.
But the harsh living conditions (infrastructure shortage and lack of a port) led to a population decline in just 20 years, while a budding tourism industry began to develop. Many islanders eventually took up only temporary residence. At present, Ons Island is the only island among the Atlantic Islands of Galicia with a stable population.
Throughout the centuries, the settlers of Ons Island paid rent to first, the Archbishop, and then to the Montenegro and Valladares families. In the early half of the 20th century, the islanders paid rent for their houses to the Riobó family, aside from having to sell them all the octopus they caught. And although rent is no longer paid today, the islanders are still considered as settlers because the houses they live in and the lands on which they’re on are not theirs.
In the last decades of the 20th century, the Ons archipelago passed through the hands of several state agencies (IRYDA and ICONA), until it was transferred to the Xunta de Galicia in 1982, and on 1 July 2002, it became part of the Atlantic Islands of Galicia Marine-Terrestrial National Park. In order to prevent damage to its environment, several protective measures have been adopted in addition to its declaration as a National Park. In 2001, Ons Island was declared a Special Protection Area for Birds. In 2004, the Ons-O Grove Intertidal Complex was declared a Site of Community Importance. Also in 2004, it was declared a Special Protection Area for Natural Values, and in 2008, it was declared an OSPAR Marine Protected Area (MPA).
The population density of Ons Island was quite high in the past and buildings are strewn around the eastern side of the island—the most compact—, from the moors to the coast. There are 9 villages that fall under the population centre of Ons:
Ons Island has a seasonal population, and only very few islanders live there all year round. From spring onwards, those who emigrated to mainland Spain go back to the island to spend summer in their homes. This, together with the hundreds of visitors and campers who go the archipelago, makes the population rise to over five hundred inhabitants.
Fishing has always been the islanders’ main economic activity. They used traditional fishing boats, of which some examples still remain. The dorna is a small, wooden boat, with a tall, curved prow and a deep keel. It is propelled by rowing, although it can also carry a sail. The gamela is flatter, with a straight stern and bottom, making it easier to handle inside the Ría de Pontevedra. The fishing methods that were used aboard these boats to catch octopus, velvet crab and other shellfish are: longline (a main line that goes into the sea, with several hooks attached) and creel (cages where bait is placed and prey can’t get out).
And while fishing provided a steady income (the catch was sold at the markets in Bueu and Cangas), agriculture and livestock farming supplemented the families’ diet and earnings. On Ons Island, there were fields planted with rye, broad beans, corn, potatoes and wheat, where the islanders worked after coming from fishing.
On Ons Island, there are many legends that intermingle with the popular beliefs and traditions of Galicia. This is because its relative isolation and the lack of services have given rise to a unique popular culture, where knowledge about medicinal plants, as well as the belief in myths and legends, stands out. The Santa Compaña (procession of souls in sorrow announcing death) is a good example of how deeply rooted some superstitions are. It is said that on Ons, it begins in Punta Centulo—originating from Noalla—and after giving the warning, it disappears in the cemetery.
Another of the most common is the evil eye. On Ons Island, it is said that to cast the evil eye on someone, you have to go to Beluso, bring a toad, put a piece of clothing from this person in its mouth and invoke the evil eye on them. To do this, you have to go to the beach, make 18 balls of seaweed, place half of them on your right and the other half on your left, throw the 9 balls on your right into the sea while chanting “Ondas do mar sagrado / Tirame o aire de morto / de vivo ou escomulgado”, and let the remaining 9 balls dry in your house’s fireplace, which should also be thrown into the sea afterwards.
It is also said that in Buraco do Inferno (a chasm measuring 5 metres across and 40 metres deep located in the south), you can hear the cries of the souls in torment for their sins. Some cries are supposedly heard when there is a windstorm. They probably originate from the sound of the sea as it crashes against the rocks and the sound of the common guillemots nesting inside it. There’s also the legend of the bull, which is about a bull with golden horns protecting us from the “world of the dead”.
There are several places of interest that you can visit on Ons. The most important one is the Ons Lighthouse, which is one of the largest and the longest ranging in Spain. It is located in O Cucorro, in the highest part of the island, and is the work of the architect Rafael de la Cerda, who built an identical one on the island of A Rúa. It was first lit in 1865 and tiled in 1932. It was one of the last lighthouses using pressurised oil lamps—together with those of Sálvora and As Sisargas—which remained, since it started using solar photovoltaic energy in 1990.
Other places of interest are the batteries in ruins (that of As Rodas to the north of the pier and that of Castelo in the south), the castro of Canexol and the castro of A Cova, the old cemetery in Canexol (which is more than 200 years old) and the modern church of San Joaquín, which was most likely built over another one much older.