"Riding the Board" is a term in diving that describes the action of landing on the springboard during a hurdle as the board is moving down toward the water instead of up and away from the water. The timing during the hurdle allows the diver to gain the most spring from the diving board.
If the diver lands on the diving board on its downward path, the diving board will then naturally rebound up and the diver will gain lift. If the diver lands on the diving board while it is moving up and away from the water (with the diver and the board moving in opposite directions), the amount of spring will be decreased.
In a forward approach in diving, the goal of every diver is to work in concert with the diving board to get the most amount of height - known as "riding the board."