The ITER Diagnostic Division is responsible for designing and procuring the First Wall Blankets that are mounted on the vacuum vessel port plugs at both the upper and equatorial levels. This paper will discuss the effects of the diagnostic aperture shape and configuration on the coolant circuit design. The Diagnostic First Wall (DFW) design is driven in large part by the need to conform the coolant arrangement to a wide variety of diagnostic apertures combined with the more severe heating conditions at the surface facing the plasma, the First Wall (FW). At the FW, a radiant heat flux of 35W/cm2 combines with approximate peak volumetric heating rates of 8W/cm3 (equatorial ports) and 5W/cm3 (upper ports). Here at the FW, a fast thermal response is desirable and leads to a thin element between the heat flux and coolant. This requirement conflicts with the desire to have a thicker FW element to accommodate surface erosion and other off-normal plasma events.