Advanced Caving in Jentilzubi Cave (Indusi)

Context The underground passage connecting the Abaro sinkhole to Jentilzubi Cave lies within the Arratia Valley, part of the Indusi karst region in Bizkaia. This wet karst landscape features striking natural formations and constant water presence, with multiple vertical shafts and technical sections. The route navigates through winding galleries that reflect the complex geology of the Urkiola Natural Park, where the echo of dripping water reverberates off the rock walls.

The Experience You’ll take part in a 4- to 5-hour caving journey starting at the Abaro sinkhole, crossing a seasonal stream and progressing through damp galleries. You’ll descend two technical rappels, including one unsupported aerial rappel requiring focus and skill. Navigate handrails, gateras, and tight squeezes, feeling the constant chill and moisture in the rock. Air currents carry the scent of thyme from the surface, while water whispers through the darkness.

For Whom This activity is designed for experienced cavers who are confident in rappelling, handrail techniques, and movement in wet, aquatic environments. A minimum group size of four is recommended, with good physical fitness and no fear of confined spaces. Not suitable for beginners, those with severe vertigo, or limited mobility.

Local Context The Arratia Valley and Urkiola Natural Park have a long-standing caving tradition, with local communities actively involved in karst conservation. The area near Baltzola Cave is a well-known destination for climbing and hiking, blending adventure with a landscape of high natural and cultural value.