A turbine airfoil for a gas turbine engine including an outer peripheral wall having an external surface, the outer peripheral wall enclosing an interior space and including a concave pressure sidewall and a convex suction sidewall joined together at a leading edge and at a trailing edge; wherein the outer peripheral wall has a varying wall thickness which incorporates a locally-thickened wall portion; and a film cooling hole having a shaped diffuser exit passing through the outer peripheral wall within the locally-thickened wall portion.