Child Drowning Necklace Alarm
A necklace that needs to be out of water periodically or it sets off an alarm that is installed by the pool. Now that would save some lives. Something colorful that the kids would wear.
You could calibrate it by having the child staying under water as long as they can, then setting that as a maximum time before alarm goes off. Thanks. Please, somebody get rich with this idea for the sake of the kids.
Reward: hearing that the government has made these mandatory for children in pools because they save lives.