Matienzo is the name of a village and a karst depression some 25 km southeast of Santander in Cantabria, northern Spain. The limestone around Matienzo is riddled with caves (up to 54 km in length) which have been extensively explored over the last 50 years by Spanish and British cavers.
Information about the area and more than 3600 caves, along with research details, cave surveys and thousands of photos can be found at the Matienzo Caves site [1] and a summary article read at [2]. Cave exploration, cave diving, geology, archaeology, geomorphology and personal recollections are all included in a wide ranging, dual language overview of 50 years of speleology in and around Matienzo - Matienzo: 50 Years of Speleology. Details can be found on the web site.