Pozo Azul (Covanera) – cave-diver only
Cave-divers only: the Pozo Azul spring at Covanera is the entrance to a flooded cave system of about 13.7 km, in the Hoces del Alto Ebro y Rudrón natural park. The blue spring pool is about 8 m wide under a limestone cliff and looks down into the cave; behind it lie sumps of up to −71 m (S2, about 5.2 km long) and a 2010 British expedition set a world record for underwater penetration here. Visitors walk up from the small car park in a few minutes and can look into the pool; only experienced cave divers may go in. The water is 9–11 °C all year.
Facts
- Region: Spain – Inland Caves, Reservoirs & Rivers
- Area: Burgos – Covanera (Pozo Azul)
- Depth: 0–71 m
- Level: advanced
- Current: moderate
- Type: cave, spring, siphon
- Coordinates: 42.735772, -3.795994 (approximate)
- Highlights: flooded cave system, 13.7 km mapped, sump S2 to −71 m, 5.2 km long, water about 9–11 °C, one of the longest cave-diving penetrations in the world
- Permit: Access to the flooded cave is limited to experienced cave divers (full cave qualification, sump experience). The sources state that a permit is needed but I could not verify the issuing body or procedure from an official page – check with the Hoces del Alto Ebro y Rudrón natural park and the Burgos provincial authorities.
- Issuer / contact: Unverified – natural park / provincial authorities (no official page retrieved)
- Tips: Full cave-diver qualification and sump experience are a must (the sources describe the flooded galleries as suitable only for researchers and expert divers; earlier accidents led to restrictions). I could not retrieve an official permit page, so ask the natural park / Burgos provincial authorities and the cave-diving clubs (Grupo Edelweiss) about access before planning. Non-divers: the spring is a short walk from the car park and free to visit.