Believe it or not, the human body is quite buoyant. With your lungs, full of air, you’d be hard pressed to sink, especially in salt water. That’s why people have no trouble snorkeling – when you lie flat on the surface with your head in the water, your weight is easily supported, whether you weigh 100 pounds or 300 (45kg-136). Add scuba equipment and you become even more buoyant. Even though scuba tanks will sink when full, divers wear buoyancy compensators (BCs), vests that not only secure the tank to the diver’s back but also contain inflatable air bladders to provide flotation on the surface. Wet suits are made of neoprene, a type of rubber that contains thousands of tine air pockets. These air cells provide insulation to prevent heat loss and in addition add considerable buoyancy. Weight is worn either on a weight belt are can be put in weight pouches that insert into your buoyancy compensator (BC). The amount of weight varies from a couple of pounds (1kg) to more than 30 pounds (14kg) depending on a variety of factors. Salt water, for instance, is more buoyant than fresh water, so about 2.5 percent more weight is required.