The GR57 is one of the three great routes of the Ria de Aveiro. Planned along the banks of the Ria, the approximately 131 km of this blue route run along paths that are as diverse as the landscapes and biotopes of a lagoon ecosystem unique in Portugal. From the salt marshes to the habitat of "Bocage" and the pine forests planted in the sandspits that hold the Ocean to the farming fields, which have coexisted with the Ria for centuries, this is a route that reveals the diversity and richness of people’s relationship with the natural world. This route connects to GR11-E9 - European Coastal Path.