Laguna de la Posadilla, Valverde

Laguna de la Posadilla is a volcanic maar lake located about 3 km from the town of Valverde, in the municipality of Ciudad Real, in the Castilla-La Mancha region of Spain. Also known as Volcán de Fuentillejos, it is one of the most distinctive examples of volcanism in the Campo de Calatrava area, a region famous for its numerous lakes formed inside ancient eruption craters.

How was the lagoon formed?

The lake fills a crater created by a hydromagmatic explosion — a violent event triggered when rising lava came into contact with a layer of groundwater. The sudden vaporization of that water caused an explosive eruption that carved out the basin now occupied by the lake. This type of geological formation, known as a maar, is relatively rare and scientifically valuable: Laguna de la Posadilla is listed by Spain's Geological and Mining Institute (IGME) as a site of international geological relevance.

What will you see there?

The lagoon stands out for its almost perfectly circular crater shape, framed by Mediterranean vegetation. Oak trees, wild pistachio, mastic shrubs, and kermes oak grow along the slopes, while reeds line the water's edge. The site is protected as a Natural Monument and forms part of the Natura 2000 network as an area of special conservation value. It draws geology enthusiasts, birdwatchers, and anyone looking for a quiet encounter with nature.

How to get there?

Laguna de la Posadilla lies roughly 3 km from the center of Valverde. Although the land is privately owned, a footpath leaving from Valverde leads to the lake, covering about 2.5 km. The walk crosses typical Campo de Calatrava countryside, and the full scale and regularity of the volcanic crater only becomes apparent once you're close.

When to visit?

Spring and autumn are the best seasons, when temperatures in Castilla-La Mancha are milder and the vegetation around the lake looks its most vivid. Summers in the region can be very hot, making longer walks uncomfortable, while winter gives the landscape a starker, more dramatic character. Bring sturdy walking shoes and water, since there are no supply points along the route.

Frequently asked questions

Can you swim in Laguna de la Posadilla? The lake sits on privately owned, environmentally protected land, so swimming and free access to the shore are not permitted — visits are limited to admiring the landscape from the path and designated viewpoints.

What makes this lake different from others in Campo de Calatrava? Laguna de la Posadilla is a textbook example of a maar — a crater formed by a hydromagmatic explosion rather than a simple sinkhole or a classic volcanic cone crater — which makes it especially interesting to geologists.

How long does the walk from Valverde take? The footpath covers about 2.5 km one way, typically taking 30–45 minutes at a moderate pace, depending on fitness level and trail conditions.

Are there other attractions nearby worth visiting? Yes, the Campo de Calatrava region is known for many similar volcanic lakes and cinder cones, which can be combined into longer routes exploring the area's volcanic history.