A man enjoying a private pool at a company party in central Israel was sucked into the subsurface when a sinkhole opened up under the pool. The ground collapsed into a void and rapidly drained all the pool water. After a four-hour rescue attempt in the town of Karmei Yosef, the body was later found 15 meters into the hole. Another man sustained minor injuries.
Pool leaks have resulted in sinkhole collapse before. The slow trickle of water can erode the soft material in a karst void. A dip can be created in the pool liner which causes more water to push through, which eventually causes the flow to start rapidly washing away the support. It’s a self-feeding mechanism. When the liner breaks, the sudden release of the water into the hole acts like drain cleaner, flushing the material into the subsurface voids. This is very rare. There must be a significant karst feature under the pool for the water to have someplace to go.