@Joe_Bondi_Beach
drowning girl out of the pool
remember your A B Cs Airway Breathing Circulation (heartbeat).
When you pull a person out of the water, if it has been less than a few minutes, they are likely to still have a heartbeat (unless they fell in due to a heart attack, or being shot, etc.) or if the water was frigid (research the Mammalian Diving Reflex). So, first check to see if they might be breathing, and or have a heartbeat. Never give CPR to a person with a heartbeat! If they aren't breathing, and have been in the water, lay them facedown, and allow any water to drain out. Then do a finger sweep to clear any mud/mucus/vomit, etc. from the mouth; you don't want to blow that into their airway/lungs! Then check to see if they are breathing. Sometimes a firm open-hand slap to the back may get the person breathing.
If they are not breathing, and a slap or two to the back hasn't spurred them to breath, then perform a "Rescue Breath" or two, and then check to see if that has restarted a person's breathing. If they still are not breathing, then use a facemask / hand-squeeze pump, or resuscitation breathing.
CPR is only done if a person's heart has stopped! In many water immersion situations, where the person is pulled out of the water in a matter of minutes, their heart is likely to still be beating.
If a person has had a heart attack, there is often vomit, or mucus in their mouth, you want to sweep their mouth, and check to see if their airway is clear before administering a rescue breath. You don't want to block their airway! As was mentioned by at least one person above; chest compressions to circulate the (oxygenated) blood is often sufficient to replicate the exhale/inhale functions of the lungs, replicating breathing.
Most of my medical training has been focused on soldiers, and other people from late teens to early fifties. Drowning/water immersion is something we must be prepared to treat. Heart stoppage due to shock-trauma is also something we may treat. Bullet wounds, or other wounds/injuries may complicate CPR (in particular broken ribs puncturing a lung(s) pr other organs!
Broken ribs during CPR, or more commonly, "crackling" cartlidge that paramedics talk about is most common for people over fifty years of age, and especially the elderly.
{edited to correct a couple of typos}