Abstract: An energyefficient routing scheme is presented for underwater acoustic sensor networks (UWASN). Firstly, the factors affecting energy consumption in UWASN are analyzed in light of underwater channels, the relationship between numbers of relay nodes and energy consumption is obtained for given sourcedestination distance. The directed diffusion routing scheme is modified in the initial diffusion phase to find the optimal route based on the geographic information between a sink node and its neighboring nodes. Simulation shows that the proposed scheme can reduce the flooding cost, select an energyefficient route, and save more energy.

Key words: underwater acoustic sensor network, energy consumption, routing, simulation