In an underwater wireless sensor network (UWSN), research challenges occur in the availability of new connectivity protocols, sensors, and utilization of energy. One of the issues is to enhance the lifespan of the network without increasing the supply, cost, and level of resources. This paper proposes a conceptual routing protocol for UWSN, known as Energy-Efficient Multipath Adaptive Routing (E2MAR) protocols, which is primarily intended for long-term control with greater energy efficiency and transmission rate. Key development conditions were set by the E2MR and forward nodes are chosen based on the performance index. Different tests are carried out by evaluating E2MR in terms of the number of live nodes, end-to-end latency, packet delivery rate, and maximum energy usage efficiently compared to some other Routing protocols. The lifespan of the network has also been greatly enhanced.