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, the authors 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. The authors did so on the basis of their interviews with four of the five surviving cave divers. The authors 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. The authors found that there was a temporary flow blocking during the collapse, but no total flow reversal within the cave. Abstract published by arrangement with John Wiley & Sons.