Pozo Azul, Natural spring in Covanera, Spain

Pozo Azul is a natural spring in Covanera where water emerges from underground caves to form a pool with distinctive blue coloring from limestone minerals. The clear water makes it easy to see into the depths where the spring originates.

Diving exploration began in 1964 in the first sump, S1, a 700 m narrow passage no deeper than -20 m, continued by Joaquín Plana of the G. E. Edelweiss. Beyond it lies the air-filled gallery called "la Burbuja", first reached in 1979 by the Standard group. By 30 August 2015 the explored underwater length had reached 13,600 m, and the cave continues.

In Covanera the spring is known as Pozo Azul, the name given locally to water that rises from depth rather than at the surface and appears blue. The stream it feeds is called Arroyo Las Pisas until it reaches the Rudrón, 250 m downstream. Brown trout live in the pool, where the water stays between 9 and 11 °C all year.

Reach the spring via a short walking path of about 300 meters from the parking area off the N-623 road near the village. The route is relatively flat and easy to navigate, making it accessible for most visitors.

By August 2015, divers had mapped 13,600 metres of submerged passages, including a 5,160-metre second sump reaching 71 metres deep and dry galleries such as "la Burbuja", first entered in 1979. The explored cave continues beyond the known sections.