Within diving there is evidence of physics. For example when leaving the board it shows projectile motion. The boy creates a force down on the board which is equal to the force of the board pushing back onto the boy. Gravity also acts on the boy by pulling him down. The boy then projects because he has less mass and has nothing stopping him from projecting upwards. Therefore the reaction is the boy being projected into the air. When he comes back down and hits the water he is no longer a projectile.