Scuba diving can be an interesting exercise, but before you jump into the water with an air tank tied to your back, it\'s important to know all aspects of it. Although the scuba water tank will sink into the water whether it is empty or full of air, it will sink faster when it is full. The scuba tanks are characterized by metal, which makes them heavy. This is intentional; Heavy tanks help divers sink. It gets heavier if you fill the scuba with air. The tank, filled with 80 cubic feet of air, weighs 6 pounds more than the empty tank. Objects sink or float in the water depending on their buoyancy. If it is filled with air and put into the water, objects such as balloons, inner tubes or rubber rafts float. The air increases the volume of these expandable items, so the weight per square inch is less and lighter than the water. It is important that because scuba tanks do not swell, the air inside them does not increase their surface area or make them more energetic. Divers breathe the air inside the tank and they become lighter. The buoyancy of the diver, coupled with the drop in air weight in the tank, makes it harder for the diver to stay underwater as the tank becomes lighter. Maria Tussing is a freelancer from South Dakota and has been working on articles since 2000. She has published articles in publications such as \"family fish and games\", \"Wonderful times\", \"Today\'s horse\" and \"Cattle Business Weekly. Tasin holds a bachelor\'s degree in journalism from chadelon State University.