When you squeeze the sides of the bottole why does the diver fall?

When you squeeze the sides of the bottle, you increase the pressure inside, causing the water level to rise and displacing the air in the diver. This added pressure compresses the air inside the diver, making it denser than the surrounding water. As a result, the diver becomes negatively buoyant and sinks. Once you release the pressure, the air expands, and the diver rises again.