As temperature rises seasonally, glacier melts and water has percolated down into lava beds. That rock formation acts as filter and water reappears as super clear spring water in the down-gradient direction, filling the fissures at this location. So, the water is being refreshed constantly. At a more accessible spot, not too far away from these fissures, there is a diving facility to explore the underwater world there. Interesting but I am not into diving....