When a diver jumps off a diving board gravity pulls him or her down to the water what is the reaction force to earth gravity?

The reaction force to Earth's gravity on the diver is the gravitational attraction that the diver exerts back on Earth. According to Newton's third law of motion, for every action, there is an equal and opposite reaction. In this case, the Earth pulls the diver down, and the diver also pulls the Earth up with an equal force.