system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: If I am submerged in a bath and I drink some of the water does the water level go up, down or stay the same?
gpt
In abstract theory, the water level stays the same.

In messy actual practice, it would go down a little, at least at first, as some of the internal parts of your body expanded without expanding the outside. Other than your lungs and any intestinal gas, there's not much "empty" space inside your body, but some of it is somewhat compressible, like a sponge.

At some point, however, that would stop and the water level would stay the same as you kept drinking and your body expanded accordingly.