Underwater Wireless Sensor Networks (UWSNs) have emerged as a promising technology for a wide range of ocean monitoring applications. The UWSNs suffer from unique challenges of the underwater environment, such as dynamic and sparse network topology, which can easily lead to a partitioned network. This results in hotspot formation and the absence of the routing path from the source to the destination. Therefore, to optimize the network lifetime and limit the possibility of hotspot formation along the data transmission path, the need to plan a traffic-aware protocol is raised. In this research, we propose a traffic-aware routing protocol called PG-RES, which is predicated on the ideas of Pressure Gradient and RESistance concept. The proposed PG-RES protocol initially detects its neighboring area using a node request message to build a routing directory that includes the communication cost to each neighboring node. Then, by adjusting the routing process according to network conditions in a proactive mode, PG-RES mitigates traffic burden in the nodes along the transmission path to the sink, so the chances of hotspot occurrence are reduced in the underwater environment. The simulation results have revealed that the proposed PG-RES protocol achieves superior performance than the other techniques in terms of average energy usage, packet delivery ratio, network lifetime, and transmission delay. The PG-RES protocol demonstrated a reliable data transmission with a packet drop ratio that was 13.92% lower than EEDOR-VA and 3.66% lower than VHARD-FS. The development of this protocol aims to support real-time applications in highly isolated ocean environments, where reliable data forwarding and hotspot handling are essential for timely data transmission.
