This dive site, known as the Gateway tunnel JOZEF within the historic Slovak opal mines, offers a unique opportunity to explore an extensive overhead environment. With 17 levels, four of which are flooded, the tunnels stretch for almost 5 km, reaching depths of nearly 70 meters below water level at their deepest point (though this specific gateway is 25m max). Divers navigate through the remnants of historical mining operations, experiencing a truly distinct submerged landscape. Extreme caution is required due to the overhead environment and soft sediments.
Due to the extremely low pH-level of the water and the complete absence of natural daylight, there is no marine life to observe within the flooded tunnels. Divers will not encounter any fish, coral, or other aquatic flora or fauna.
The water temperature remains consistently cold at 4-5°C, necessitating appropriate dry suit diving equipment. Visibility can be good initially at around 20 meters, but divers must maintain excellent buoyancy control to avoid disturbing the soft sediments, which can quickly reduce visibility to near zero. This site is exclusively for experienced cave divers, and is not suitable for snorkeling or standard freediving due to the overhead environment and cold.
