 All right, now let's talk about a fence alarm because these work just like door alarms, but they're designed to be used on the fence gates around your pool for an added layer of protection. You can also look into a pool alarm because these are designed to detect a splash that occurs when a child falls into a pool. A CPSC study looked at three types of pool alarms and found that the best performers were underwater alarms compared to the less reliable options of floating pool alarms or wristband alarms that you actually have your kids wear.