Located in the present-day Aiako Harria Nature Reserve, Oiartzun also had an important level of maritime activity and controlled the mouth of its namesake river that was then much deeper than it is today. In addition, it was an excellent supplier of raw materials for shipbuilding (forges, forests, etc.). It is worth mentioning the mines of Arditurri that as early as Roman times (1st-2nd centuries) transported and shipped the main minerals extracted: lead, iron and silver, from the port of Pasaia. Throughout history, the mines of Arditurri have not stopped their activity and they are open to visitors today.
Lezo, like Pasaia, has developed from its origins by the sea and was, along with Errenteria, an important part of the port of Pasaia. It also had shipyards. Its perfectly preserved historic quarter shows maritime elements on its façades, although the best known element is undoubtedly the Santo Cristo de Lezo, a beardless image that, according to legend, appeared in the 15th century floating in the sea, and to which numerous miracles have been attributed throughout history. As an interesting aside, the first miracle attributed to the Santo Cristo de Lezo occurred in 1570, in favour of some sailors from Lezo and Pasaia who were in Newfoundland.
It preserves the biggest historical quarter of the region with more than 20 elements catalogued as monuments or of cultural interest. In the 16th century, Errenteria was an important centre for the construction of boats, since it had the first Royal shipyard to open in Gipuzkoa: the Basanoaga Royal Shipyard. In its historical quarter, this maritime legacy is still visible, where the Casa del Capitán (16th century) stands out, today housing the Costume Centre.