While shark attacks do occur, they are a fairly minor cause of mortality for scuba divers (far more important to be certain that there is enough air in the tank and that the regulator sucks properly). Surfers are more at risk than divers, since they spend more time on the surface. The only shark related fatality to a scuba diver was to a commercial fisherman at the surface on his scooter near San Miguel Island (AKA Shark Park); Cal F&G won't allow their divers in the water there.
Dspite the impression you get from Hollywood movies, shark sightings and encounters are not routine.
_________________________
Geezer in Chief