We also analyzed energy consumption problem of UWSN and existing schemes for prolonging network lifetime. Then we proposed our new algorithm to prolong network lifetime based on current achievements in scientific research. The basic idea is to decrease and balance the nodes’energy consumption. In the algorithm we emphasized the underwater network model and routing protocol. In the routing protocol a combined transmission is advanced. A node transmits to its neighbors by probabilities; and nodes residual energy is also considered, if it is below a threshold, the node will refuse to be a relay and avoid a deadlock in the network, then we improved the network reliability. Besides,if some nodes dead advanced,other nodes could find the appropriate route when they send message to the sink,so can assure the network runs normal.We compared our energy efficient routing protocol and traditional routing protocol in a detailed simulation. In direct transmission dominant (where all nodes transmit to the base station directly) and multi-hop transmission dominant routing, the furthest or nearest node to the base station will die first, while in our routing protocol, energy consumption of nodes is balanced and network lifetime is prolonged at the same time.
