Sima de los Simancos

Sima de los Simancos is a cave located in the municipality of Cabrejas del Pinar, in the province of Soria, in the Castile and León region of Spain. It's one of the more notable caving sites in the area, known to local speleologists and visited by caving enthusiasts, though it does call for some basic preparation and gear before heading in.

What will you find inside?

The interior consists mainly of a single long gallery running roughly east to west, sloping gently downward. The tunnel keeps fairly consistent proportions throughout — about 4 metres wide and 6 to 8 metres high — giving the sense of moving through a natural stone channel. Deeper in, you'll come across gravel deposits and accumulated branches, carried in by water whose flow noticeably picks up during the rainy season.

The cave also serves as an important shelter for bats. Large patches of guano in several sections point to it being used as an overwintering site for a bat colony. Bones of livestock — sheep, goats, and even mules — have also been found on the cave floor, suggesting the space was historically used as a natural pen or shelter for herds.

How do you get there?

Three entrance shafts lead into the cave. The main one, and the best equipped for descent, is known as P18 — roughly 18 metres deep, dropping vertically onto a large debris cone at the base, mixed with branches and organic sediment. Descending through this shaft requires proper caving equipment (harness, ropes, helmet with a headlamp) and is best done with someone who knows the terrain, or with an organised caving group — this isn't a site suited to unguided, inexperienced visits.

Cabrejas del Pinar itself sits in Soria province, surrounded by the extensive pine forests typical of this part of Castile. It makes a good base for anyone curious about the geology hidden beneath the interior of the Iberian Peninsula, where numerous caves and sinkholes — a "sima" in Spanish literally means a deep pit or chasm — form a network of underground attractions.

When should you visit?

The dry season — late spring through summer and into early autumn — is the best time to explore, when water levels inside are lower and moving through the gallery is safer. During heavy rains, the water flow through the tunnel increases considerably, making entry harder or sometimes impossible. Winter is also worth factoring in: that's when the bat colony overwinters inside, so it's worth keeping noise down and limiting time in the deeper sections out of respect for the animals.

Frequently asked questions

Is Sima de los Simancos suitable for beginners? Not entirely. Descending through the P18 shaft requires basic caving gear and some prior experience. Anyone without preparation should join a guided group or a local caving club instead of going alone.

How long does it take to explore the cave? It depends on the route and how much you want to see — a short look at the main gallery can take one to two hours, while a fuller exploration of the system, including access and return, takes longer.

Do animals live in the cave? Yes, it functions as an overwintering site for a bat colony, visible from the large guano deposits in parts of the tunnel. Visitors should stay quiet and respectful of this natural habitat.

What does the name "Sima de los Simancos" mean? "Sima" is the Spanish word for a deep cave or chasm, typical of limestone terrain. The name "Simancos" most likely refers to a local place name tied to the surrounding land within the municipality of Cabrejas del Pinar.