The surface of the earth consists of 71 percent water. In recent years, research has focused on using underwater sensor networks (USN) to monitor and manage these aqueous environments. Research on the communication protocols in Terrestrial sensor networks (TSN) has been well investigated and various protocols proposed. In contrast with terrestrial wireless sensor networks, the characteristics of acoustic communication lead to challenges in deploying fully functional and operational USNs. In our proposed architecture, we present a new energy efficient opportunistic routing protocol (EE-OR). The proposed protocol is a novel energy-efficient opportunistic routing algorithm for USNs. The protocol deals with the issue of ranking of nodes during candidate set selection while reducing energy consumption and keeping the packet delivery ratio at a satisfactory level. In order to evaluate the performance, we used two common metrics that have been used for routing protocols in USNs; energy consumption and packet delivery ratio. Simulations were carried out in NS-2 with Aqua-Sim. The performance of the proposed protocol is compared with the standard DBR protocols. The comprehensive performance evaluation attests the benefit of EE-OR as compared to the mentioned protocol in terms of energy consumption, end-to-end delay and packet delivery ratio.