A heat exchanger is provided. The heat exchanger (40) provides a first plurality of tubes (50) and a second plurality of flow passages (52) which furcate near one of the first (42) and second (44) manifolds into two or more furcated flow passages and subsequently converge to exit the heat exchanger. The plurality of furcated flow passages are intertwined, reducing the distance between flow passages (50,52) containing each fluid therebetween to improve thermal transfer. Further, the furcations create changes of direction of the fluid to re-establish new thermal boundary layers within the flow passages to further reduce resistance to thermal transfer.