Operation track dem kids

I would like 11 durable (they couldn't break it even of they use a chainsaw or pliers), waterproof (fully submerged for several hours) and discreet (doesn't look obvious) ankle bracelet trackers for children that track at the least 100 miles. I would like them to only be taken off with a key or code of some sort, basically I want to be the only one to be able to take the trackers off. My main focus is for them to be tracked in real time at all times. Up to a week or more on one charge.