An airfoil (400; 500; 700; 900; 1100; 1300; 1400; 1500) for a gas turbine engine, the airfoil comprising: an airfoil body having a plurality of cavities formed therein, the airfoil extending in a radial direction between a first end and a second end, and extending axially between a leading edge (402; 506; 706; 906; 1106; 1506) and a trailing edge; a first core cavity (406; 502; 702; 902; 1102; 1502) within the airfoil body; a second core cavity (408; 504; 704; 904; 1104; 1504) located within the airfoil body and adjacent the first core cavity, wherein the second core cavity is defined by a first cavity wall (414; 512; 712; 912; 1112; 1312; 1412; 1512; 1712; 1812), a second cavity wall (514; 714; 914; 1114; 1514) opposing the first cavity wall, a first exterior wall (410; 516; 716; 916; 1116; 1516), and a second exterior wall (412; 518; 718; 918; 1118; 1318; 1418; 1518) opposing the first exterior wall, wherein the first cavity wall is located between the second core cavity and the first core cavity and the first and second exterior walls are exterior walls of the airfoil body; wherein the first cavity wall has a chevron shape extending into the second core cavity and defines a first surface (524; 724; 924; 1124; 1326; 1426; 1524; 1724; 1824) angled toward the first exterior wall and a second surface (526; 726; 926; 1126; 1526; 1726; 1826) angled toward the second exterior wall; at least one first cavity impingement hole (416; 520; 720; 920; 1120; 1322; 1422; 1520; 1720; 1820) formed within the first surface, wherein the at least one first cavity impingement hole is configured to direct a first impingement flow from the first core cavity through the at least one first cavity impingement hole to impinge upon the first exterior wall to form a first high momentum jet of impingement air thereon; and at least one second cavity impingement hole (418; 522; 722; 922; 1122; 1522; 1722; 1822) formed within the second surface, wherein the at least one second cavity impingement hole is configured to direct a second impingement flow from the first core cavity through the at least one second cavity impingement hole to impinge upon the second exterior wall to form a second high momentum jet thereon; characterised in that the at least one first cavity impingement hole has an oblong shape with a long axis (1356; 1456) oriented at about 90° relative to the first exterior wall. an airfoil body having a plurality of cavities formed therein, the airfoil extending in a radial direction between a first end and a second end, and extending axially between a leading edge (402; 506; 706; 906; 1106; 1506) and a trailing edge; a first core cavity (406; 502; 702; 902; 1102; 1502) within the airfoil body; a second core cavity (408; 504; 704; 904; 1104; 1504) located within the airfoil body and adjacent the first core cavity, wherein the second core cavity is defined by a first cavity wall (414; 512; 712; 912; 1112; 1312; 1412; 1512; 1712; 1812), a second cavity wall (514; 714; 914; 1114; 1514) opposing the first cavity wall, a first exterior wall (410; 516; 716; 916; 1116; 1516), and a second exterior wall (412; 518; 718; 918; 1118; 1318; 1418; 1518) opposing the first exterior wall, wherein the first cavity wall is located between the second core cavity and the first core cavity and the first and second exterior walls are exterior walls of the airfoil body; wherein the first cavity wall has a chevron shape extending into the second core cavity and defines a first surface (524; 724; 924; 1124; 1326; 1426; 1524; 1724; 1824) angled toward the first exterior wall and a second surface (526; 726; 926; 1126; 1526; 1726; 1826) angled toward the second exterior wall; at least one first cavity impingement hole (416; 520; 720; 920; 1120; 1322; 1422; 1520; 1720; 1820) formed within the first surface, wherein the at least one first cavity impingement hole is configured to direct a first impingement flow from the first core cavity through the at least one first cavity impingement hole to impinge upon the first exterior wall to form a first high momentum jet of impingement air thereon; and at least one second cavity impingement hole (418; 522; 722; 922; 1122; 1522; 1722; 1822) formed within the second surface, wherein the at least one second cavity impingement hole is configured to direct a second impingement flow from the first core cavity through the at least one second cavity impingement hole to impinge upon the second exterior wall to form a second high momentum jet thereon; characterised in that the at least one first cavity impingement hole has an oblong shape with a long axis (1356; 1456) oriented at about 90° relative to the first exterior wall.