Scuba Diving is far more likely to kill you than any shark.
Here's a few nasty things that can happen to divers..
1) Drowning - Suffocation as you breathe in water
2) Barotrauma - Your lungs over expand and burst or ear drums can implode etc..
3) Gas embolism - Air under pressue is forced into your blood causing a heart attack.
4Decompression illness - Can appear after a dive and and can kill or paralyse your legs for life.
5)Nitrogen Narcosis - Can stop you thinking clearly so that you do something stupid and drown.
6) Gear failure - You can suddenly lose all of your air at depth when part of your gear suddenly fails and drown. (Having personally had an o ring burst underwater and see my air rapidly escaping, I can confirm that it is alarming)
Hope this helps.