Humpleu System-The Big Cave Of Firei Valley- Poenita Swallow-Hole Cluj-Napoca

Humpleu system is located in Bihor mountains massif, in Doda Pilii area. It is classified as a natural monument and the underground river that runs through it, is the longest in Romania-with a length of 5 km, only from the perspective of basic route without taking into account the feeders. The main entrance is made through the Big Cave in Firii Valley.

Access is allowed only for specialized speo-tourism with a guide and specific equipment, after the approval of the Commission of the Patrimony of Apuseni National Park.

The Big Cave of Firii Valley is located at an altitude of over 1000 metres, it is the second longest cave in Romania. It was discovered in 1984 and consists of two facilities, superior-fossil and inferior active, floors separated by distances ranging from 30-50 m one under another. The level difference is of -314 m, meeting almost all of the karst phenomena known since now. It consists of a system of halls and galleries, four of them being the biggest halls of the cave discovered so far in Romania - Hall of giants, a volume of 2 800 000 mc, second in Europe, Hall Gabor Hallasi -1 300 000 mc, Dance Hall – 480 000 and Dan Coman Hall -410 000 mc. In the active gallery lies the longest underground river in Romania, in some passages the distance between the water surface and the ceiling is of 20-30 cm.

Poenita swallow-hole was discovered in 1978, is located at an altitude of 1400 m and has two cavities. The junction between the two cavities was made in 1989. From a morphological perspective, the pothole can be structured in several sections up to final altitude of -258 m. The section between 0 and 70 m, the small meanders are linking several large wells. The section between -70 and -160 m is characterized by sectors of straits and small jumpers and an underground river. In the section between -160 m and -258 can be found a cascade of large dimensions with developing in bell or in fractures. In this section there is a gallery of 150 m, very straight, approximately horizontal, crossed by a river.