THE LITTLE WONDER ATLAS · AGES 6–12 WITH A GROWN-UP
How a submarine changes depth
A submarine manages weight and buoyancy to travel underwater.
Follow the wonder
Choose a numbered step to highlight its place in the picture.
At the surface, upward buoyancy balances the submarine’s weight.
Letting water replace air in ballast tanks increases the submarine’s total mass.
Changing buoyancy helps it submerge. Moving submarines also use control surfaces to change depth.
Compressed air pushes water out of the main ballast tanks, increasing buoyancy relative to weight.
LITTLE WONDER LAB
Predict. Explore. Discover.
No score and no timer. A surprising result is a discovery too.
1 · Make a prediction
Choose a prediction to unlock the controls.
2 · Change one thing
A simplified model, not a real-world measurement.
Less ballast water makes this submarine lighter. Buoyancy is greater than its weight, so it rises.
0 / 3 settings explored
Water pushes up. Weight pulls down. Changing ballast helps a submarine rise or sink.
3 · Keep your discovery
Compare at least two settings to unlock your badge.
TRY ONE QUESTION · HINTS ARE WELCOME
What enters the main ballast tanks to help a submarine dive?
Take your time. You can read the map again.
Show me the answer
Water
For grown-ups: sources and learning notes
Reviewed 28 September 2026. These are introductory explanations; the diagrams simplify real structures and processes.