The “personal swim buoy” was first developed about 20 years ago in Asia to enhance visibility of swimmers in open water races, and a few years later, it was embraced in North America by the International Swimming Hall of Fame in Florida, who also saw the safety value of this device.  It is an inflated device that is attached by a short tether to a waist belt.  When swimming, it is towed behind the swimmer, occupying a space over the backs of the knees, where it is just out of reach of the finish of any arm stroke, and just short of the feet, so it does not interfere with kicking.  And perhaps counter-intuitively, it causes no drag whatsoever—the bow wave created by the swimmers’ advancing shoulders creates an eddy behind the Swim Buddy that actually pushes it forward—really!  This device is therefore not noticed in any sense, and swimmers often forget that they are even using it.