Abstract: Nof and Paldor (Safety Sci 2010;48:607–14) suggested that resonance in the air pockets in the Indian Spring cavern might have contributed to the 1991 collapse. Here, we extend the resonance theory to one pocket in the cavern and a very broad basin that serves as the other branch of the U-tube. Our methodology is to apply familiar fluid dynamics principles to the situation that occurred in the cave. We did so on the basis of our interviews with four of the five surviving cave divers. We dissected their testimonies to arrive at a physically plausible scenario determined on the basis of a fluid dynamics application to the natural flow in the cave, the flow induced by the compressed air released by the divers and the mudslide. We found that there was a temporary flow blocking during the collapse, but no total flow reversal within the cave.