A blade outer air seal for use in a gas turbine engine, the BOAS including a plurality of first diffusion and impingement cooling air cavities separated by stiffener ribs, each diffusion and impingement cavity being connected to a cooling air supply cavity through a first metering and impingement hole. Each diffusion and impingement cavity is connected to a plurality of trenched diffusion slots that open onto the surface of the BOAS and form a series of V-shaped slots. A plurality of second metering and impingement holes connect each slot to the respective first diffusion and impingement cavity. The trenched diffusion slots are angularly offset from a normal direction to the BOAS surface, and the second metering and impingement holes are offset at about 90 degrees from the slots so that both diffusion and impingement cooling occurs within the slots. The array of separated diffusion and impingement cavities and metering holes allow for the cooling flows and pressures to be regulated for each area of the BOAS.