Underwater Wireless Sensor Networks (UWSNs) use acoustic waves to communicate in underwater environment. Acoustic channels have various limitations that can be low bandwidth, a higher end to end delay and path loss at certain nodes. Considering the limitations of UWSNs, energy efficient communication and reliability of network UWSNs has become an inevitable research area. The current research interests are to operate sensors for a longer time. Currently investigated research area towards efficient communication have various challenges, like flooding, multiple copies creation path loss and low network life time. Different from previous work which solve these challenges by measuring the depth, residual energy and assigning hop-ID’s to node. This article has proposed a novel scheme called Radius-based Courier Node (RMCN) routing. RMCN uses radius-based architecture in combination with cost function, track-id, residual energy, and depth to forward data packets. The RMCN is specifically designed for long term monitoring with higher energy efficiency and packet delivery ratio. The purpose of RMCN is to facilitate network for longer periods in risky areas. The proposed routing scheme has been compared with DBR and EMGGR in respect of alive nodes left, end to end delay, delivery ratio and energy consumption.