For years I’ve wondered the answer to this question. Finally the question has been answered.
The answer to this question depends on the gun being used. We will answer this question for three popular types of guns: hand guns, long range rifles, and shotguns.
Most hand guns like the 9mm will penetrate the water up to 7 feet.
If you are deeper than 8 feet, you probably be safe from someone who is firing at you from outside of the water with a handgun.
Long Range Rifles:
Bullet travel much faster when fired from a high powered rifle than a handgun . The interesting thing about this is, a long range rifle penetrates the water much less than a handgun.
Test has shown that a bullets shot from high powered rifles will only penetrate the water up to 3 feet.
If you are deeper than 3 feet, you probably be safe from someone who is firing at you from outside of the water with a long range rifle.
Shotgun tests have shown to penetrate the water deeper than 6 feet.
Exact depth tests were not done, however researchers believe you will be safe from shotgun bullets if you are deeper than 8 feet.
Note: If the bullet is shot from an angle, the penetration will be less.
ANSWER: YOU WILL BE SAFE FROM BULLETS IF YOU ARE DEEPER THAN 8 FEET!
Mythbusters did a great episode answering this question. We recommend that you check it out.