Have you ever swum at East Coast Park and got a mouthful of seawater? Yuck — so salty!

But rain and rivers are not salty. So where does all that ocean salt come from? Let's find out — tap Next to begin! 👉

First, a taste test 👅

Tap each glass to "taste" it. Can you guess which water is salty before you tap?

Land is full of hidden salt 🪨

Rocks and soil have tiny bits of salt and minerals locked inside them. You can't see it, but it's there!

Tap the rocks to crack them open and find the hidden salt grains.

Salt found: 0 / 3

Rain washes the salt to the sea 🌧️➡️🌊

When rain falls, it slowly dissolves that hidden salt and carries it into streams and rivers. Rivers flow downhill… all the way to the ocean!

💧 Send the salty water down!

Here's the big secret ☀️

The sun heats the ocean. Water turns into vapour and floats up to make clouds. But here's the trick:

The water leaves… but the salt stays behind!

☀️ Heat it up (step 0/3)

Salt keeps coming, water keeps leaving 🔁

This has been happening for billions of years! Rivers keep adding salt, and the sun keeps taking only the water. So the salt builds up and up.

There's one more secret source. Tap the seafloor to reveal it 👇

You be the scientist 🔬

The sun heats a cup of salty seawater until the water disappears. What is left in the cup?

Here's the whole story in 4 steps:

• 🪨Rocks and soil on land hold hidden salt.
• 🌧️Rain dissolves the salt and rivers carry it to the ocean.
• ☀️The sun makes water evaporate — but the salt stays behind.
• 🔁This repeats for billions of years (plus underwater volcanoes), so salt keeps building up.

Great work, young scientist! Next time you taste seawater, you'll know exactly why. 👏