Guard Tour Systems for Resorts

Watchclocks for resorts

The Detex ProxiPen system is the best for this application.

They are waterproof.  Drop them in a pond or pool, or off a dock.. Get it back the following day, it still works.

The checkpoints are small round disks the size of a quarter.  They are black.  You can paint them, you can bury them in plaster.  Put them behind a glass window, or on the other side of a door or painting.  Discreet.  Very discreet.