Wilson and Flynn used back bunkers behind greens. The original bunkers were shallow and above green level. With the green sloping away from the player, the shot requirements were pretty severe. Merion East has back bunkers on 1st, 3rd, 4th, 5th, 6th (back right), 9th, 10th, 13th, 14th and 17th holes and Merion West has one behind the 7th and 13th (Richie Valentine). An approach that lands in any one of these can be real trouble.