A major Spanish caving expedition took place in the summer of 1964 and British-led caving expeditions have been occuring up to 3 or 4 times a year since the late 60‘s. The length of known cave passage in the area has risen from some five or six km to 399.2km (May 2021). On average, three to five kilometres of cave are found each year, although in 1989, 2008 and 2009 over 15km, 13km and 14.8km respectively was surveyed. Cave diving has resulted in new discoveries and collaboration with Spanish groups has resulted in new cave exploration. An area map shows the major caves.

Permission to explore is given by the Cantabrian government and Spanish speleological authorities within both geographical (about 106km²) and time limits. Good relations are kept with the villagers, the caving authorities, and other spanish caving groups. We have had the support of the Ghar Parau Foundation which recommended grants for many years. Recent grants to the Matienzo Caves Project Expeditions can be seen here.
  During the expeditions, many cavers camp in the field behind Casa Germán. The restaurant here is also the HQ - a computing and drawing up area. Hostel accommodation is available at La Taberna in the village, at Casa Tomás in Ogarrio and at the Restaurante Pension Anjana near Ramales. There are also a number of self-catering facilities within a few kilometres of Matienzo.