system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How does one not become severely injured when jumping from extreme heights into a small amount of water?
gpt
As the saying goes, it's not the fall that hurts, but the sudden stop at the end.

The trick, then, is to make the stop *less sudden.* If you fall onto something soft, rather than coming to a stop suddenly, you stop more gradually as the thing you're landing on deforms or displaces under you.

But water isn't all that great for this. Water is *incompressible,* meaning it doesn't squish like a pillow when you land on it. Instead it has to move out of your way, which it can only do so fast. So lowering your hand into a sink of water hardly feels like anything at all, but doing a belly flop into a pool stings like a mother.

That's why diving is hard. It's not just the fact that a well executed dive looks good and all that; it's that you *have* to enter the water in just the right way to keep from getting bruises or even broken bones.

So the short answer is that water *can* slow you down safely and effectively, but only if you use it just right. Use it wrong, and it's not that much better than plowing full-speed into concrete.