The man who gave this city its name died on a riverbank, far from his people, at the hands of the Payaguá people, searching for a mountain of silver that never existed. Juan de Ayolas was one of the sixteenth-century Spanish conquistadors who led the early exploration of the Plata basin and the Paraná and Paraguay rivers, and his story —like that of so many of those adventurers— ended tragically. Ayolas took part in the expeditions that, setting out from the Río de la Plata, sought both a route to the riches of the continent's interior —the mythical 'Sierra de la Plata'— and control of the great rivers penetrating northward.
Juan de Ayolas played a prominent role in those first years of the conquest: he arrived with Pedro de Mendoza's expedition to the Río de la Plata (1536), sailed up the Paraguay River and on February 2, 1537 founded the Fort of Nuestra Señora de la Candelaria on its bank. From there he pushed into the Chaco seeking a link with Peru, reached the gates of present-day Bolivia (the 'Province of Charcas') and, on his way back to the fort, was attacked and killed by the Payaguá, around 1537-1538. He would be succeeded in government by Domingo Martínez de Irala. His figure became associated with the often tragic adventure of those first incursions into the heart of South America.
That a southern Paraguayan city, on the Paraná, bears his name is a tribute to that founding stage of the European presence in the region. The place name recalls that these waters and these shores were the scene, almost five centuries ago, of the first encounters —and clashes— between the conquistadors and the native peoples of the basin.
The region where Ayolas stands today belongs to the department of Misiones, a name that is no accident: it alludes to the old Jesuit missions or reductions that flourished in the south of present-day Paraguay during the seventeenth and eighteenth centuries. Before and during that era, these lands were inhabited by Guaraní-speaking peoples, who lived on the banks of the Paraná and inland, drawing on the resources of the river and the woods.
From the seventeenth century, the Jesuits organized reductions in this area such as San Ignacio Guazú —considered the first in the territory of present-day Paraguay—, Santiago, Santa María de Fe and Santa Rosa de Lima, among others. In those towns, thousands of Guaraní lived under a singular religious, social and economic system, which left a notable artistic legacy (carvings, altarpieces, imagery) and urban legacy, today one of the great cultural heritages of southern Paraguay.
Although Ayolas as a city is much later, this mission backdrop is part of its regional context. The proximity to those historic towns places the modern river city within a territory laden with Guaraní and Jesuit memory, which enriches the area's cultural offering and connects the riverside present with a deep past.
The event that changed the destiny of Ayolas forever was the construction of the binational Yacyretá hydroelectric dam, one of the largest engineering works in South America, built jointly by Paraguay and Argentina on the Paraná River. The project was part of an era of major hydroelectric undertakings in the region, alongside the equally gigantic Itaipú dam, in the east of the country.
The construction of Yacyretá mobilized enormous resources, machinery and thousands of workers, and completely transformed the landscape of southern Paraguay: the dam wall and the powerhouse were built, and a vast reservoir was formed that altered the course and level of the Paraná, flooding extensive areas. For Ayolas, located right in the works zone, this process meant accelerated growth, with an influx of population, infrastructure, services and a new urban dynamic.
The dam left as its legacy not only electricity generation but also infrastructure and associated areas —including wildlife refuges created as an environmental mitigation measure for the reservoir's impact. Yacyretá turned Ayolas into a city tied to energy and the river, and laid the foundations of its modern development.
The creation of the enormous Yacyretá reservoir had, like every large dam, a strong environmental and social impact. Raising the level of the Paraná flooded extensive areas of shores, islands, woods and wetlands, altering ecosystems, modifying wildlife habitats and affecting riverside populations who had to be relocated. These effects made Yacyretá a much-debated case in environmental terms within the region.
As part of the mitigation measures, the binational entity that administers the dam promoted the creation of wildlife refuges and protected natural areas on both sides of the river. These spaces seek to conserve the region's species, offer alternative habitats for wildlife displaced by the reservoir and develop animal management and rescue programs. Today they house birds, mammals and other species typical of the Paraná's environments.
For the visitor, these refuges add a natural dimension to the trip to Ayolas: they let you observe wildlife and understand, at the same time, the tensions between energy development and environmental conservation. They are part of the complex legacy of a work that brought energy and growth, but also profoundly transformed the river and its surroundings.
Past the era of the great works, Ayolas found in sport fishing and nature tourism a new identity and a reach that extends beyond its borders. The waters of the Paraná around Yacyretá proved excellent for dorado fishing, the 'river tiger', and the city established itself as one of the region's most recognized destinations for this activity, a regular host of tournaments and competitions.
Sport fishing, often practiced under catch-and-release rules to preserve fish populations, draws enthusiasts and competitors from various countries each year, generating economic activity, specialized hospitality and guide and boatman services. Along with the dorado, the waters hold other species of the great South American rivers, which enriches the experience.
To that appeal are added the Yacyretá dam itself —an imposing work that can be visited—, the wildlife refuges, the waterfront on the Paraná and the proximity to the Jesuit and mission towns of the department of Misiones. Thus, today's Ayolas combines its energy origin with a tourist vocation tied to the river, fishing and nature, within the map of deep, river Paraguay.