Škocjanske jame – Reka sumps (Ledeni dihnik, Marchesetti lake)
The Reka river disappears into the Škocjan Caves and flows through a giant underground canyon to terminal sumps. Slovenian divers passed the Ledeni dihnik siphon around 1990 and found more than 200 m of new passage, and in 1991 Janko Brajnik and Samo Morel swam through the siphon in Marchesetti lake just before Dead Lake, finding large passages with a river and lakes. Current exploration aims to link the system with Kačna jama about a kilometre away. In December 2025 a 49-year-old Slovenian diver died in the roughly 200 m long, 20 m deep Ledeni dihnik siphon in Martel's Hall during a research dive; recovery took 16 hours and over 100 rescuers.
depth: 0–21 m