The Irrawaddy dolphin is similar to the beluga in appearance, though most closely related to the killer whale. It has a large melon and a blunt, rounded head, and the beak is indistinct. The dorsal fin, located about two-thirds posterior along the back, is short, blunt, and triangular. The flippers are long and broad. It is lightly coloured all over, but slightly more white on the underside than the back. Adult weight exceeds 290 lb and length is 7.5 ft at full maturity.