DIAGRAM OF FIELDS SURROUNDING SNORKELER, SCUBA DIVER, AND SURFER
from the "Sea Change Shark Shield" [website]
How It Works:
The Shark Shield™ generates an electrical field that, it is believed, is detected by the shark through its sensory receptors, known as the Ampullae of Lorenzini, found on the snouts of all predator sharks. Once detected by the sharks' sensors, the field causes muscular spasms that result in the shark being deterred from the area.
The field is projected from the unit by two electrodes, which create an elliptical field that surrounds the user.
In order for the Shark Shield™ to operate effectively the unit must be switched on when the user enters the water, left on for the duration of the users time in the water, then switched off as the user exits the water.
(text and image reprinted with permission)