This site has been explored and surveyed by the Grupo Espeleológico de Santander del C.A. Tajahierro. Their survey is published in Exploraciones en Solorzano (Santander) in Los Sótanos de la Tierra, No. 5, 1980, Santander (ref. 1980a). Unfortunately the entrance position (along with many others in the publication) is very unreliable although attempts have been made to alter the given Madrid grid reference through a Greenwich grid reference to an ETRS89 grid reference, seen above. The cave is in the Tanaguillo area of Solórzano.
The site, named by the GES, has not yet been located but it is "on the right at the end of the road leaving the Town Hall square." There are at least two, if not three, entrances.

Reference: anon., 1980a; anon., 2014b (Easter logbook)
Entrance picture :
Underground pictures :
Video :
Detailed survey : from anon., 1980a
Line Survey :
On area survey :
Survex file :