Saltwater Density Tower | Ocean Science Experiment

See how salt changes the sea—layer by layer!

Arthur says: “From the floating Red Sea to deep, dense ocean currents, salt makes a splash in ocean science! Let’s build a colorful tower to see density in action—no scuba suit needed.”

🔧 What You’ll Need:

• 4 clear cups or glasses
• Warm water
• Table salt
• Food coloring (4 colors)
• Spoons
• Dropper or pipette
• Tall clear container (or large cup)

🧪 Steps:

1. In each of the 4 cups, mix water with different amounts of salt:
• Cup 1: 0 tbsp (just water)
• Cup 2: 1 tbsp salt
• Cup 3: 2 tbsp salt
• Cup 4: 3 tbsp salt
2. Add a different food coloring to each cup and stir until dissolved.
3. Start with the saltiest (Cup 4). Use a dropper to gently layer the colored water into your tall container.
4. Add the next saltiest (Cup 3), then 2, then 1. Pour slowly and carefully—don’t mix!
5. Watch the tower form: the saltiest water stays on bottom, and fresh water floats at the top!

📘 What You’ll Learn:

Salt increases water’s density, making it heavier. That’s why salty ocean currents sink and swirl deep below the surface—moving heat, nutrients, and even whales around the globe!

Pocket Fact: The Dead Sea is so salty (over 9x saltier than the ocean) that people naturally float without sinking!