The first thing that people ask themselves when they first set foot on the Salt Valley of Añana is: Why is salt produced here and not someplace else? The answer is not easy and it's necessary to resort to a geological phenomena known as Diapir. Roughly speaking, it consists in that the current place of the saltern was covered by a big ocean more than 200 million years ago that dried up, leaving a layer of salt several kilometers thick. With time, this layer was covered by new stratum that hide it definitely. Because of the different densities between layers (similar to what happens when we mix water with oil), in some very specific points of our territory the salt emerged to the surface. And those are the places where we can find the internal salterns.

But how to carry out the exploitation of these seams? The answer is simple: either by mining techniques, or taking advantage of the sources of salt water (brine) that are created after the passage of fresh water through layers of solid salt.

The saltworks of Añana belong to the last group and have the luck to count with several springs that provide around 260.000 liters of brine daily with a concentration near to saturation point.