Can you blow up a balloon without blowing? You will need: a plastic bottle, an inflatable balloon, a knife, scissors, a container with water Procedure: Cut out the bottom of the bottle. Pull the inflatable balloon on the neck of the bottle. Then dip the bottle vertically into water. Explanation: Water penetrates into the bottle because of the snipped bottom. Air has lower density, so it is always above the water. The water pushes the air into the balloon. Try, on the contrary, to depress the balloon into the bottle. Air and water do not mix together. Air is always on top.