If a closed bottle is turned upside down, immersed in water and opened, the water will not fill the bottle. Why?

For water to flow into the bottle, an air-free space is required.

The air in the bottle is gas. It shrinks to some extent when exposed to water, this allows you to free up a small volume to accommodate the water, but does not allow it to fill the entire bottle.

Air does not leave the volume of the bottle either through the walls of the bottle or through the water, since gas cannot penetrate through solid and liquid bodies.

When the bottle is tilted, air will escape from it.