How do submarines go up and down?
Quick Answer
Submarines go up and down using ballast tanks. They let water in to become heavier and sink, and they push water out with air to become lighter and rise.
Why This Story Works for Bedtime
It’s a steady, satisfying ‘control and balance’ explanation—water in, water out. Calm systems thinking can feel grounding at bedtime.
Story at a Glance
RECOMMENDED AGES
7-11 years
READING TIME
2 min
Story Synopsis
A submarine can dive deep and then return to the surface. This story explains how it controls that movement. Miluna shares that submarines have ballast tanks—spaces that can hold either air or water. When the submarine lets water into the tanks, it becomes heavier and sinks. To rise, the submarine pushes water out of the tanks using compressed air, making it lighter so it floats upward. The submarine also uses fins to steer and tilt. The tone stays gentle and clear, focusing on balance and control rather than danger. Curiosity stories like this make big machines feel understandable and safe to think about.
Story Excerpt
Have you ever watched something float in a bathtub like a toy boat and then pushed it down into the water A submarine is like a boat that can choose when to float and when to sink The big idea is about how heavy something is compared to the water it takes up Water can hold up things that are light enough for their size and it lets…
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In One Glance
Submarines change depth by changing how heavy they are. Ballast tanks can fill with water to increase weight and make the submarine sink. When air pushes the water out, the submarine becomes lighter and rises. Control surfaces help steer and adjust angle. The story explains buoyancy calmly and shows how engineering uses simple rules to move through water.
Frequently Asked Questions
It explains ballast tanks—water in to sink, water out with air to rise.
Ages 7–11.
Yes—clear, rhythmic cause-and-effect.
No. It avoids danger and stays gentle.
It builds confidence in understanding technology and encourages reading for ‘how things work.’