Háromszög Cave is a small yet fascinating cave tucked into the Oszoly massif in the Pilis Mountains, within the Duna-Ipoly National Park. Its name means 'triangle cave' in Hungarian, a fitting title given the distinctive triangular cross-section of its entrance passage.

The surrounding area is classic Pilis limestone terrain - steep, wooded slopes dotted with rocky ridges, popular with both hikers and rock climbers exploring the nearby Óra-fal (Clock Wall). The cave itself formed through corrosion in Upper Triassic Dachstein limestone. After squeezing through a short entrance corridor, visitors reach a spacious chamber where they can finally stand upright and admire the mineral formations, including abundant moonmilk (montmilch) coating the walls.

How to get there

• From Óra-fal on Oszoly - heading north along the base of the rock face for about 100-150 metres brings you right to the cave entrance, at roughly the same height as the base of the wall; easy to moderate route

Practical information

• The cave can be visited in ordinary hiking clothes
• A torch/flashlight is recommended to properly see the moonmilk deposits on the walls
• The cave is around 5 metres long

The cave was first referred to as Háromszög-barlang in the literature in 1997, the same year it was surveyed and mapped in detail for the first time, having previously been just one of many small, unnamed cavities scattered among the rocks of Oszoly.