This cave is not in #Spain, actually, but in #France at the #border between #Baxenabarre (Lower Navarre, in Basque language) and #Nafarroa #Navarra, in the French-Spanish #border but the cave proper is situated on French territory, at the commune of Estérençuby (1/11) https://twitter.com/TheKarstMan/status/1359223887452643330

... #Ezterenzubi (in Basque), meaning "zubi", bridge. So, in Basque means "bridge of the gorge" because of the deep valley formed especially by #Nive (fr.) #Errobi (bq.) river, an affluent of the main river #Adour (fr.) #Aturri (bq.) that flows into Atlantic Ocean waters (2/11)

...below #Bayonne #Baiona at Boucau mouth in Bay of Biscay (fr. Gascony). Of course, it's very interesting as a geological formation, because Alpine orogeny gave rise to the formation of granite peaks flanked by layers of limestone like in this classical case you show. (3/11)

Anyway, it's common among #Navarra #Nafarroa #Baxenabarre #BasseNavarre #Lapurdi #Labourd ancient Basque provinces #border not to coincide with the watershed. So, some rivers and their affluents of #Bidassoa #Bidasoa, #Nive #Errobi, #Nivelle #Urdazuri have their source (4/11)

on one or the other side of the #border in a few metres to some kilometres. I have the privilege of knowing region. I suggest you, apart from visiting Harpea's Cave (meaning "the place under the rock" in Basque) in a heavily wooden areas of Pyrenees, the iconic (5/11)

... #Irati forest, with beech as primary tree (on Autumn, it's spectacular!), but also #Kakueta Canyon, formed by erosion 15,000 years ago by river #Uhaitxa, reaching a height of 350 metres at some points. It's situated on the Eastern Basque ancient province of #Soule (6/11)

#Zuberoa, the #Orreaga #Roncevaux Pass, in #Navarra, famous by Battle of Roncevaux Pass in 788 when Roland died fighting against Basques after the withdrawal of Charlemagne from Muslim Saragosse giving place to the famous old French "Chanson de Roland" a Medieval epic poem (7/11)

and situated on French Way of St. James Pilgrimage between Saint-Jean-Pied-de-Port #DonibaneGarazi and #Pamplona #Iruñea, capitals of both Navarres. It's also interesting #LaRhûne #Larrun, a peak situated less of 10 km of the sea at 905 m, just in the middle of the (8/11)

...French-Spanish #border and between #Lapurdi and #Nafarroa. You can arrive it by a nice train where you pass from 175 to 900 m in only 4 km and see North Navarre, #Gipuzkoa until surroundings of #Donostia #SanSebastián and all Basque French coast and #Landes with famous (9/11)

...bathing city of #Biarritz. Finally, I can't stop talking about #Isturitz and #Oxocelhaya caves, with human remains of #Magdalenian. If you love History, Nature, Gastronomic, little pretty citied with a high standard of living #BasqueCountry is your choice! And of course(10/11)

...for #border freaks like me! Sorry for this long thread. I only wanted to make some remarks and I've finished giving a tourism master class... Thanks for sharing. I loved to remember happy times! Hvala za deljenje. Rad sem se spominjal srečnih časov!

P.S. Sorry for typing mistakes that don't make the text incomprehensible.