The prehistoric stone circle - believed to date back to at least 5,000 B.C. - has delighted archaeologists.
It was actually first discovered in 1926 but the Valdecanas reservoir was built and filled in 1963 and the stones have only become fully visible four times since.
Now, as Spain faces its worst drought in 60 years, the water has receded enough to make it visible again.
Historical and tourism associations have advocated for the stones to be relocated to dry land for preservation.
The structure is officially called the Dolmen of Guadalperal. Dolmens are stones arranged vertically to support a flat top, often to serve as tombs.