Entrambasaguas is a small municipality located in the autonomous community of Cantabria, Spain, 25 km south of the Bay of Santander.

Iron was mined here from prehistoric times, used in the Royal Artillery Factory of La Cavada, which supplied the Armada, and eventually brought some wealth during the Renaissance.

Mount Vizmaya forms the gentle relief of Entrambasaguas; it is a 249 meter high rugged limestone massif with various caves and the vestiges of a Cantabrian castle serving as a vantage point at its peak.

[4] The Miera is one of the main rivers of Cantabria and has been declared a 'site of community importance' for being a natural area that helps preserve habitats and endangered species.

After passing through San Roque de Riomiera it disappears from the surface, embedded in rough limestone slopes up to the town of Liérganes, where it resurfaces again.

The Aguanaz is also born by a karstic spring located in the district of San Antonio, which after crossing Entrambasaguas and Hoznayo passes through the natural bridge of the Fuente del Francés joining the Miera River in Villaverde de Pontones.

The forests also contain oaks, beeches and birches, pine trees and a barberry shrub (arbusto espinosa) used in homeopathy, with fruits that are edible when steamed.

The Navajeda cave was first explored in 1922 by a priest named Jesús Carballo, who found Palaeolithic strata and burial sites from the Bronze Age.

[5] Two sites dating back to the Middle Ages are the upper necropolis of Entrambasaguas from the 9th to 12th century, and Mount Vizmaya in Hoznayo, featuring ceramic shards and construction from the time of the Reconquista.

Some of the places during that period appear in medieval documents, as for example Navajeda, whose inhabitants in 1407 claimed the privilege of being "exempt of extraordinary tax" and being linked to Santa Maria of Santoña.

[5] Past economic activities in Entrambasaguas define a good part of its cultural heritage, and are directly related to the rivers that run through them.

The Spa at the Fuente del Francés, the many water mills, and the Max milk powder factory owe their existence to the river Aguanaz.

Historical documents indicate that the flow of these rivers was generally sufficient to keep them active during droughts when other nearby mills stopped, which brought business to Entrambasaguas.

[10] A former milk powder factory, (fábrica de productos dietéticos Max) still stands in San Antonio, a district of the town of Entrambasagas.

Berlowitz chose Entrambasaguas as a location for the new factory because it had cows, good forage, and the water of the river Aguanaz, which was not only clean but also had the right temperature.

[9] The Puente Agüero bridge over the Miera river, built in the Middle Ages, was key for east–west travel; its present state is from 1737, as restored in 2001.

[17] The judicial district for Entrambasaguas is Medio Cudeyo, with main seat in Solares, where for example title registry for real estate recording is located.

[citation needed] The economy of Entrambasaguas has traditionally been based on agriculture, growing crops, and pasture for dairy cattle, which dominated until the 1980s.