Avenc Hanna Svacbroc

The entrance gives access to a shaft of about 11 metres, with a narrow section at its base that leads to a chamber 5 metres high. The floor is full of blocks, through which opens a 2-metre gallery that leads to a 6-metre shaft. This shaft connects with two side chambers, and its sloping floor reaches, at 15 metres, the base of an 18-metre shaft. At this point a dig allows access to a 14-metre shaft with a narrow, elongated section. The cave continues, but its narrowness and the rocks prevent progress.

Before reaching the 18-metre shaft, in a small chamber we find a passage 1.5 metres wide by 0.3 m high; once past it we find a rock bridge that hinders progress but gives access to a small chamber of 1.6x1.75x1 metres. At the bottom of this small chamber we find a more comfortable passage that places us on a small step, the bottom of which, after digging, leaves a passage of 0.3x0.6 metres; this gives access to a 4.5-metre shaft, at whose base we find two continuations that a few metres further down join in a 23-metre shaft; at the bottom opens a 13-metre-long by two-metre-wide joint. Continuing along the joint we find a parallel ascending flue; there is a “gour” two metres wide by 1.5m high. After passing a descending 2.5-metre ramp we reach a new 7-metre shaft, still having to overcome another narrow passage, behind which, at -65 metres depth, a new obstruction marks the end of the cave.

The walls of the 5-metre-high chamber are covered by a stalactitic flowstone. The 6-metre shaft connects with two highly decorated side chambers. Continuing along the joint we find a parallel ascending flue with much formation.

The first exploration was carried out on 2 March 1969 by members of the Equip de Topografia Alpina de la Creu Roja de Sant Cugat and a small group of speleology enthusiasts who at that time were at the Vallvidrera delegation of the Centre Excursionista Àliga, who reached -43 metres depth.

In early February 1988 members of the GES of the Club Muntanyenc Barcelonès dug out the final passage and reached -55 metres depth.

In 2010, between the months of March and May, Tony Romero, Jorge Sánchez and Raúl Vilchez, members of SIRE – UEC del Prat de Llobregat, starting from a small decorated chamber located before the 18-metre shaft, carried out various digs that led them to discover a new, highly decorated route, as well as reaching a new maximum depth of -65 metres in this well-known pit of the Garraf.