This site is described on the web site of the Sociedad Espeleológica Alto Duero who have explored it. It would appear that the entrance has been located with GPS but the altitude (in brackets above) is wrong when plotted on 1:5000 maps.

A 20m diameter entrance has the first pitch of 10m which leads immediately onto the second, choked pitch of 17m. About 10m down the final pitch there is a window onto a small parallel shaft of 7m.

Reference: SEAD website; file
Entrance picture: on the SEAD website
Underground picture(s):
Detailed survey:  elevation on the SEAD website
Line survey:
On area survey:
Survex file: