This is excerpted from Surfer Today's article "How to survive a shark attack". I've left out all the more commonly known stuff about avoiding dawn/dusk, muddy water, bleeding in the water etc. Particularly to the point is the bit on "If the shark grabs you with its mouth". Are you feelin' me, homeboys?
If something brushes or bumps you underwater
Leave the water straight away to investigate. Minor bites in water are often not felt when they occur, and bleeding into the water can entice a shark back for more.
If you spot a shark
Stay cool, but shout loudly to warn others in the area. Don't antagonize or try to scare the shark away. Leave the water as quickly and unexcitedly as possible.
If you can't leave the water
Be very still and stay quiet. Keep your eyes on the shark as it swims. Sharks often retreat from prey, then circle back to gain speed and strike. Get out of the water as soon as it's safe to do so.
If you are diving and are approached by a shark
As above, stay very still. If you are holding any fish or catches, release them, then swim to safety when possible.
If you are circled or bumped
Circling and bumping mean the shark is either curious or intent on attacking. In either case, you should assume you are in imminent danger and be prepared to defend yourself.
Use anything you are carrying as a weapon, as a last resort utilizing hands and feet. Strike at the sensitive gills and eyes with repeated, short, sharp jabs. Be relentless. Hit as hard as you possibly can until the shark gives up and leaves.
If the shark swims toward you in a zig-zag motion
Back up against something - or someone - solid. Defend yourself as above. Don't give up until the shark does.
If the shark grabs you with its mouth
Be as hostile and vicious as possible. Latch onto the muzzle of the shark with any free limbs to avoid being thrashed. Then claw, kick, elbow, and generally endeavour to injure the eyes and gills. Do not play dead. The shark will simply attempt to swallow its catch.
Get to shore as calmly and quickly as possible, instructing anyone nearby to ring for an ambulance. If you have a bite and are able to apply pressure to the wound, do so right away, while leaving the water, to minimize blood loss.
If you see someone has been bitten
1. Help the victim to shore and keep them warm by wrapping them in the nearest available towel or cloth.
2. Apply pressure directly to wounds with any available cloth or fabric. If blood soaks through, do not remove the original cloth; simply add more as needed. Apply force also to pressure points directly between the injury and the heart. Common pressure points include the groin area, above the elbow, and behind the knee.
3. If pressure points do not slow the bleeding, and medical help is not immediately available, a tourniquet may be the solution. Wrap the wound in a stretchy fabric as tightly as possible, and insert a stick or rigid pole between the bandage and skin. Twist to tighten until blood flow slows considerably or stops. Use this measure only under extreme circumstances, where no other choice is available.
4. Elevate the bleeding limb to a position above the heart; if possible, at least 12 inches.
5. Keep the victim still. If a limb appears disfigured, or broken bones are suspected, leave the limb in place. If possible, pad with soft material, applying ice to the outside of the pad.
6. If shock is suspected, treat appropriately: call 911 or your local emergency number, lay the person down, begin CPR if necessary, and don't let him/her eat or drink anything.
While shark encounters are no doubt on the rise, attacks resulting in death or injury are still exceedingly rare.