Planinska jama – Pivka branch sump
Planinska jama is the resurgence where the underground Pivka and Rak rivers meet before emerging as the Unica. The Pivka branch ends in a sump: the first diving attempt was made in January 1964 in 5 °C water with simple 5 mm wetsuits, and later explorer Tomo Vrhovec recorded the through-sump as 445 m long and deeper than 50 m for most of its length. Around 1.5 km of flooded passage (air distance) towards Pivka jama remains unexplored. The connection with the Postojna system is the long-standing goal of Slovenian cave divers.
Tiefe: 0–50 m