In embodiments, a heat exchanger includes a tube configured to transfer a first fluid. The tube includes an outer surface configured to exchange heat with a second fluid as the second fluid flows over the outer surface of the tube. The tube also includes an inner surface defining an interior configured to contain and transfer the first fluid, and a plurality of surface features integrally formed as part of the inner surface. The surface features may extend radially inward toward the interior, and are configured to increase a surface area of the inner surface to improve heat exchange between the tube and the first fluid.