Underwater Wireless Sensor Networks (UWSNs) have peculiar characteristics such as high propagation delay, limited bandwidth and high error rates. Therefore, communication protocols for UWSNs are highly required to cope with them. Specifically, the design of an efficient routing protocol for UWSNs is one of the most important challenges. The routing protocols can take advantage of the localization of sensor nodes. However, the localization itself is a crucial issue in UWSNs, which remains to be solved yet. Hence, the design of a non-localization based routing protocol is a preferable alternative. In this paper, we therefore propose a non-localization based routing protocol named MRP (Multi-layered Routing Protocol) for UWSNs. In MRP, the concept of super nodes is employed. The super nodes are the nodes having high capacity such as high energy and transmission power. Our proposed protocol, MRP, consists of two phases: layering and data forwarding phases. During the layering phase, multiple layers are formed by the super nodes, whereas, in the data forwarding phase, data packets are forwarded based on these layers. Based on the simulations using NS2, we observe that our proposed routing protocol, MRP, contributes to the performance improvements.