Mission critical applications impose the require-ments of reliability and network efficiency on Underwater Wire-less Sensor Networks (UWSN). Innovative routing solutions are therefore required for efficient data forwarding. In this paper, we propose a cooperative routing scheme for UWSNs to enhance network performance. Many cooperative communication proto-cols are developed investigating physical and MAC layer aspects to improve link efficiency in harsh underwater environment, however, at network layer, it is still largely unexplored. In this paper, Cooperation is employed at network layer in existing non-cooperative routing protocol, Depth Based Routing (DBR), to increase its reliability and throughput. Potential relays are selected on the basis of depth information. Data from source node is cooperatively forwarded to the destination by relay nodes. The simulation results show that CoDBR gives 83% more throughput, 98% more packet acceptance ratio and 90 % less packet drop in the stable region as compared to non-cooperative scheme.