Alarmed Pool Fence

We thought that it was going to be enough to install a fence around the backyard to keep our children in and unwanted guests out but unfortunately that has not been the case. We have a lovely backyard and kids from all over the neighborhood love our pool. So much so that my kids and other kids love to play in it when I am not looking. The pool fence is not enough and I would like to know if there is some sort of alarm system I can put around the pool that whenever a boundary is penetrated the alarm will signal me.