## 1 Introduction  
Marine Underwater Sensor Networks (MUSNs) present the possibility of communication underwater and on the water's surface [1]. Marine vehicles use this technology, known as the Underwater Wireless Sensor Network (UWSN) [2; 3; 4; 5], for communication. The sensor nodes are deployed in and on the water's surface, forming a Wireless Sensor Network (WSN) in the water environment [6]. Over 70% of the surface of the earth is occupied by water, and communication is essential, especially in underwater environments, such those primarily used by marine vehicles [7]. There is no proper cabling, and there are no other centrally controlled internet facilities. Thus, marine vehicles use wireless communication with the help of ad hoc networks [8]. Cooperation is a scheme by which a network is enhanced and helped to improve its performance [9]. This scheme is based on relay optimization, in which different relay sensor nodes are deployed on the surface and in underwater environments [10]. Communication in water/underwater is different from in terrestrial areas; therefore, underwater communication uses acoustic channels to transfer data packets from one sensor node to another [11]. A limited frequency range is also used that is not able to effectively penetrate to a significant distance [12,13]. Therefore, relay optimization nodes are deployed, which are able to boost the transmission signal and shorten the distance among sensor nodes [14, 15, 16, 17, 18, 19, 20]. The proposed method is focused on marine communication and its utilization in ocean communications. Numerous Autonomous Underwater Vehicles (AUVs) have been deployed in underwater environments [21, 22, 23]. Numerous other sensor nodes have also been deployed as part of the underwater communication system, as shown in Figure 1. Multiple nodes are deployed in underwater communication, each with its own characteristics and features [24, 25, 26, 27]. Pressure sensors, moving sensors, moving relay sensors, moving sink nodes, and AUVs are used in communication scenarios [28]. The ranges of nodes are increased underwater, creating massive problems for marine vehicles that are not able to effectively communicate and transfer data [29, 30]. Relay and cooperation schemes can improve network performance and deliver data by means of advanced and fair mechanisms [31, 32, 33, 34]. Sensors are used in computing due to their easy installation and deployment. Different types of sensor are used, including underground sensors, terrestrial sensors, pressure sensors, etc. [35, 36, 37]. Another sensor type is the underwater sensor, which has the unique ability to communicate underwater using acoustic signals [38]. Marine vehicles use these sensors for communication in underwater environments, and this technology is referred to as Marine Underwater Sensor Networks (MUSNs) [39, 40, 41, 42, 43, 44, 45, 46, 47]. These networks are established by marine forces and other parties for whom the acquisition of information and knowledge regarding the sea and life in the sea is of interest [48, 49, 50, 51, 52, 53]. These sensor nodes have a limited communication range, and are equipped with batteries with limited charge, thus limiting computation. Due to the high pressure and continuous resistance in the water, communication becomes difficult. Relay optimization and cooperation are processes that can boost and enhance underwater communication. Path and packet loss often occurs in this scenario, thus requiring a robust and reliable routing scheme. Figure 1: Illustration of cooperative relay-based scheme for MUSN. To address the described issues and to avoid path and communication loss in marine communication systems, in this article, we propose a cooperation and relay optimization approach to boost the network performance. The proposed protocol will make it possible to transfer data across the minimum distance and to avoid any path loss occurring while using the marine communication system.