Can my suspect hide underwater to survive gunfire?

Let me tell you something about water and bullets that Hollywood has been getting catastrophically wrong for about seventy years. A standard 9mm round — which is what roughly ninety percent of federal officers carry — loses the vast majority of its lethal velocity within three to five feet of entering water. That's the shallow end of a public pool.

The bullet doesn't just slow down. It destabilizes. It tumbles. It cavitates. By six feet of water column, you've got a hunk of metal drifting at you with the same threat as a strongly-worded letter. It will bruise you. It will not kill you.

Now — the entry wound is a different story. If your bad guy takes a round the instant he hits the water, or in those first twelve to eighteen inches, he can absolutely be killed. I worked a river pursuit where the round caught him as he was diving forward at the waterline. Did he get into the water clean, or did he catch one going in? Two completely different stories.

Here's what nobody talks about — the officers at the edge of that pool are almost certainly violating about fourteen use-of-force policies by shooting into the water. If your bad guy is submerged and no longer presenting an immediate lethal threat, the justification for deadly force gets very thin very fast.

There's also the ricochet problem. Rounds fired at a shallow angle into water don't stop — they skip. They deflect. They come back out at unpredictable angles. Your scene, if you're writing it well, should have at least one officer screaming at the others to stop shooting.

The real question is what happens next. Because the bad guy doesn't have unlimited oxygen. If officers maintain perimeter — which is what the textbook says — the suspect has to surface eventually. I worked a drainage retention pond in August — guy lasted maybe four minutes before he came up gasping. Four minutes felt like forty. That waiting is the scene your writer brain should be interested in. Not the shooting. The moment he has to choose between drowning and coming up to face whatever's waiting. That's where the psychology lives.