That and the seriously scary fishy things that you encounter....shudder....
DD1's a keen diver and was telling us about a "stroppy teenage octopus" she once encountered. She and her companions spotted it and swam towards it for a closer look and possibly a photo, at which point it disappeared into a hole in the rock and grabbed a stone back over the hole...for all the world like slamming the door!
I share your admiration for the great work done by search divers, who are rarely commended for the tough but essential job they do.
Had a try dive once...enjoyed it, but not enough to go again...will stick to snorkelling. You can still enjoy seeing the wildlife and gorgeous underwater scenery, but without the panic, sore ears and undignified waddling on land with tons of air on your back!