Tremeo Well Trail

Since ancient times, the Pozo Tremeo has been perceived as a dangerous place, a belief supported by various legends, such as the disappearance in its waters of a couple who fell into it while resting on the branch of an oak tree. The ancients also believed, due to the dark color and salinity of its waters, that the Pozo Tremeo was an “eye of the sea”—that is, a hole through which seawater emerged.

The well has even been used to predict the weather, as noted in this excerpt from Pascual Madoz’s 1845 work *Geographical, Historical, and Statistical Dictionary of Spain and Its Overseas Territories*:

“Within its municipal boundaries there is a well called Tremeda, which has never been known to run dry, and which the inhabitants consult to predict atmospheric changes by throwing in a clump of earth covered with aquatic weeds, which always drifts toward the edges; if it heads toward the northeast, the weather is fair and agricultural work can continue; if it takes another direction, the weather is unpredictable. It should be noted that the piece of earth—or ‘barometer,’ as it is called—remains on the northeast side or any other side for as long as the good or bad weather lasts. Educated members of the local community have described this phenomenon to us, and this account is corroborated by several others who have witnessed it, including our esteemed friend and collaborator Mr. Pío de La Sota.”

In reality, the well was formed because the surrounding terrain is karstic—that is, soil composed of limestone that, over time, dissolves and collapses. As part of the subsoil sank, water became trapped in this sort of natural “hollow.” The accumulation of clay helped seal off this basin, allowing it to fill completely with water after the end of the Ice Age—also known as the Würm glaciation—approximately 10,000 years ago.

To visit it, there is a short and easy trail that starts from the town of Rumoroso:
https://es.wikiloc.com/rutas-senderismo/senda-del-pozo-tremeo-59264833