Add to cart FLAT LEAD DIVE WEIGHT 2 lbs $13.95 1. What are diving weights used for? Diving weights are used to balance buoyancy when you are diving underwater. This provides you with a way to offset the buoyancy of the gases in your own body, your wetsuit and your air tank. Weights are also used to provide effective positioning in the water. This helps you to stay in the right position to move around easily. Weights can be placed on the ankles and air tank to help adjust buoyancy.