system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How do big ass ships like aircraft carriers actually float on water while carrying the weight of aircraft, engines, controls, etc?
gpt
Buoyancy is what holds up a ship. A ship displaces a certain volume of water — the ship “makes a hole” in the water of a certain size. If the volume of the ship inside the hole is lighter in weight than the water would be, it floats. 

Water is _heavy_, and the interior of a ship is mostly air, really.

A cubic foot of air weighs very little (like, .08 pounds). A cubic foot of seawater weighs 64 pounds.