What to do, if you are attacked by shark? If you are attacked by shark, you have no other option than to fight, for if you don't show resistance, your chances to survive are reduced to minimum. Every scuba diver should know that gills, snout and eyes are a shark's most sensitive and vulnerable body parts. Therefore beat, kick, push at those places as vigorously as you can. Many scuba divers who were unlucky to get exposed to a shark's attack while scuba diving fought back and in most cases did survive.
The point is that even for known men attacker sharks a human is not a normal prey to hunt for, and many bites are done just out of curiosity to see what it tastes like. So the chances a scuba diver would rebuff a shark's attack are essential.
The other danger a wounded scuba diver might just die because of severe bleeding and the loss of blood. Therefore resurfacing and getting out of the water as soon as possible is vital. The vast majority of scuba divers who dove for decades didn't even see a shark, and the chances of being attacked by one statistically are reduced to minimum, though there certain shark infested areas like in Australia or off California shores in the USA where scuba divers are at much greater risk of becoming victim.
As for Ukraine, here scuba diving is completely safe, because both Black and Azov seas are not inhabited by anything bigger than two species of shark that pose no threat for scuba divers. These are Katran (Prickly Shark, Dogfish) and a small spotted Stsillium (Cat Shark). The Dogfish can sometimes grow up to 2 meters, while the Cat Shark will hardly ever grow to exceed three feet in length. Both Katran and Stsillium are not dangerous to humans, even if in relation to fish they behave like real evil and violent predators.
Related: Shark bites in the shallow waters of the Gulf of Mexico off Sanibel Island.