Why does deep water squish you?

Swim down to the bottom of a pool and your ears start to ache, and a balloon gets crushed small. Up at the top, nothing. What is the water actually doing to you down there? Let's find out — then try to fool it.

1Two things to know about water

Water is heavy, and weight pushes down

You need just two ideas. Watch each one for a second:

Water is heavy

A bucket of water is HEAVY. Now imagine a whole tower of water stacked up high — that's a huge amount of weight.

Weight presses on what's below

Anything heavy presses on whatever's under it. So a tall stack of water presses hard on whatever sits at the bottom.

2So what makes the squeeze?

Two ideas about where the squeeze comes from

Idea 1 — how WIDE

The "more water all around" idea

Maybe a balloon gets crushed because there's just so much water surrounding it. A giant wide lake holds way more water than a skinny tube, so a lake should squeeze harder… right? Keep this one in mind.

Idea 2 — how DEEP

The "tall stack on top" idea

Or maybe what matters is only the water stacked directly above you — its weight pressing straight down. The deeper you go, the taller that stack, the bigger the squeeze. Two very different ideas. Soon you'll test them.

3Your turn — dive the balloon

Lower the balloon and watch the gauge

Here's a sealed air balloon in a tank of water. Drag it down with the depth slider and watch two things: the pressure gauge climb, and the balloon shrink.

squeeze on the balloon
TOPDEEP DOWN

4Now try to fool the squeeze

Wide lake vs. skinny well

Same balloon, same depth — but you can change the shape of the water. A giant wide lake holds a flood of water. A skinny well holds barely any. Which one crushes the balloon harder?

Guess before you find out

You'll put the balloon at the very same depth in two shapes: a giant wide lake (tons of water) and a deep skinny well (hardly any water). Where does the water squeeze the balloon harder?