> Mesothermal, sulfidic groundwater (up to 1 mM in H2S) originating from an artesian sulfidic aquifer underlying the region enters at the bottom of the cave’s lower passages. This results in a constant flow occurring tens of centimeters to 1 m below the water surface at flow rates of about 5 L/s

https://pmc.ncbi.nlm.nih.gov/articles/PMC10672346/

Right, so it was sealed only in the biological sense, which makes sense since there needs to be an inflow of energy