CBSE Class 9 Answered

As you float, your weight presses down into the water; the water presses back, pushing you up. When you get into the pool, your body displaces a volume of water (the "hole" in the water that your body fits into). As long as the water your body displaces weighs more than you do, you float. This is basically Archimedes' Law. You weigh less than the water you're in, because your lungs are full of air, like a balloon, and like a balloon, the air in your lungs lifts you to the surface naturally.