Pico Tres Mares, Montaña Palentina Natural Park

The Tres Mares or Tresmares peak is a mountain between Cantabria and the province of Palencia located in the Sierra de Híjar, between the valleys of Polaciones, La Pernía and Campoo-Los Valles, in Spain. Its summit is the vertex of the angle formed between the aforementioned mountain range and the Cordel mountain range that closes the Circo de Tres Mares or Calgosa. It has an altitude of 2175 metres above sea level according to the National Geographic Institute and other sources, or 2172.6 metres above sea level according to the Government of Cantabria. From its western slope extends the Peña Labra mountain range, which seen from La Pernía looks like an extension of the Sierra de Híjar. Its rocky crest is formed by the outcrop of quartzite conglomerates from the Triassic. At its foot, on the north side, are the Pidruecos and Calgosa meadows, where the springs of the Ebro are located, and the slopes of the Alto Campoo ski resort, one of which reaches its summit.

From its viewpoint, somewhat lower than the summit of the neighbouring Pando or Cuchillón, there is a clear view of the mountains of Campoo and Saja to the sea to the north, the Picos de Europa to the northwest, Fuentes Carrionas and the Montaña Palentina to the west, the Castilian plateau to the south, and the valleys of Valderredible and Merindades to the Montes de Ordunte.