4006: Castaño, Sima del
Riolastras 30T 456279 4805069 (Datum: ETRS89. Accuracy code: U) Altitude 318m
Length 12m Depth 12m
Area position

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. (In this case, the site appears to be well outside the 2014 permit area).
The site, named by the GES, has not yet been located - but it is apparently very difficult to find.

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