Pozo Azul is considered by many to be the best cave in Europe in which to train, and in fact it is very popular amongst the Spanish cave instructors. The entrance is a welcoming clear blue basin, 150m (flat) from the car park in the little village of Covenera, North of Burgos. The first and second sumps are separated by a beautiful 300m long dry section, although most of this can be done in the water, leaving only some 30 or so meters of more challenging terrain between the sumps.

The first sump has a maximum depth of 21m (average around 10m) and high floor to ceiling profiles that meanders some 700m to the dry section. The beige colored walls with salient cracks and formations provide some very nice scooter rides. The second sump is a lot larger in width and the lower flow allows more silt to gather on the floor and walls. This second sump is in active exploration (notably by Jason Mallinson in 2007) and has been extended to 3530m, reaching a maximum depth of 71m.