Island of A Altura Nature · Santiso, Terra de Melide, A Coruña Illa da Altura, formed by the construction of the Portodemouros reservoir on the river Ulla, covers an area of 58.14 hectares and is one of the largest islands in inland Galicia. It belongs to the parish of Beigondo, in the municipality of Santiso, and is surrounded by the reservoir's arm on the river Iso; only when the water level drops does an isthmus form linking it to land, towards the neighbouring parish of Viñós, already in the municipality of Arzúa. It rises 81 metres above the reservoir's maximum level, which makes for a maximum altitude of 325 metres above sea level. Its entire territory is woodland, not subject to any farming or livestock use. Photo: Maria zaos (CC BY-SA 4.0) What to see and do in Santiso