Keeping the sharks off the swimmers along the Natal Coast in South Africa is the business of the Natal Shark Board (NSB). A combination of a museum and a research lab- oratory, the NSB, situated on the cliffs above the Umhlanga Rocks lighthouse on Indian Ocean just north of Durban, was set up in 1957 primarily to develop anti-shark measures. But through the years it has developed a feeling of cama- raderie for the sharks and strongly discourages their elimination in any form.

However, to ensure the safety of the human beings at the same time, the NSB has now come up with a unique shark repellent gadget called Protective Oceanic Device or the POD. It works by wrap- ping the wearer in a 120-volt electrical field. Sharks are so keenly attuned to electrical impulses in the muscles of their prey that they can detect the equivalent of the current created by 2 elec- todes kept 1,000 miles apart~ The POD runs on battery and can be built into a surfboard or clamped to a scuba trunk.