They say you're far more likely to be hit by lightning, but that takes into account most don't dive.
Of course, a shark is more likely to be attacked by a human the other way around, but that is no comfort to any human bitten or eaten!
Yeah murky water or swimming on the surface at night by yourself in areas with known large sharks is dicey. Under those situation I would prefer to have at least 9 other divers within a few feet of me...that way my chances of being the one attacked is reduced by 9-fold, lol.
I listened in on a presentation by a Northern California urchin diver of 30 years and had to quantify how often he would encounter a great white underwater. He say's something like:
" I would see one about once a month. What typically happens is you are busy working away, grabbing urchins and stuffing them in your bag, and you get this odd feeling, and we would turn around, and there would be a 8-20 foot great white shark behind you looking at you from about 5 to 10 feet away. When we turn around and look right at them they always sort of get up and slowly swim off."
Of course, his tale of one of his urchin diver buddies getting attacked by a great white was a bit different I should say.
Seems they all dive on hookah rigs and one guy was near the surface on his way up and a huge great white made an ambush ascent on him and bit down but hit his rope harness and hookah hose instead which started spewing air. he and the shark got hung up in his rope together and the great white turned after missing for another attack and the rope would jerk the diver just out of the way of his opened jaws at the last second, so it would turn and attack again....and this happened a dozen times as the deck crew who saw and knew what was happening were all frantically struggling to pull him to the boat like he was some sort of shark lure. The urchin diver was getting jerked around violently during each successive attack till they finally managed to drag him on board and cut the rope.
The guy refused to dive for years after that even though the few urchin divers who possess the rare, coveted commercial urchin license make really good money.
The guy at our meeting authored the following book: