## 1 Introduction
It is basically the base station that provide a connection to the physical environment, where the gathered data is processed, broken down, and displayed according to the application's requirements [9]. To reduce the use of power resources and extend the network lifetime path while delivering data, energy efficient routing methods are necessary. Data must be transferred between the sensor nodes and the base station, which necessitates the use of routing algorithms. Energy conservation is a critical concern for extending the network's lifespan. However, the routing protocols are classified based on the operation that is utilized to fulfil the functions of a UWSN. For example, proactive protocols where the data is transferred using a pre-defined route, i.e., low-energy adaptive clustering hierarchy (LEACH) and power efficient gathering in sensor information systems (PEGASIS) [20]. On the other side, UWSNs place a great priority on building energy efficient routing protocols. In order to gather data in underwater habitats with minimal energy use, a number of routing techniques have been devised and published in the literature. The routing techniques took the characteristics of the devices and the sensor Rx nodes specs into account. Reactive protocol where the rout is established on demand dynamically, i.e., (TEEN), ad hoc on-demand distance vector (AODV), dynamic source routing (DSR) [21]. Whereas hybrid protocol are the ones where all the routs are first originated and then enhanced at the sending time of data. This hybrid protocol retain the concept of both proactive and reactive protocols, i.e., [21]. Routing protocols that are opted for energy efficiency in a UWSNs mainly consists of four different architectures, i.e., 1D, 2D, 3D and 4D architecture. A one-dimensional (1D) UWSNs architecture is the one, in which the sensor nodes are self-contained. Every sensor node is an independent network in itself that is in charge of sensing, processing, and relaying data to the remote station [5; 22; 23]. This style of architecture is known for its simplicity, where a node can be a floating buoy that detects underwater characteristics or a floating buoy that can be deployed underwater for a particular period of time to collect data [24], and then float to the surface to broadcast the collected information to the remote stations. In 1D-UWSNs, the nodes can communicate utilizing acoustic, optical or radio frequency (RF). Additionally, the topology of 1D-UWSN is star topology, which means that transmission between the sensor nodes and the remote station is passed on via a single hop [25]. The architecture of 2D-UWSN is made from a cluster of sensor nodes placed underwater. It consists of a cluster head with a fixed position that does not changes with functionality or time in the network. Each cluster node collects data and transmits it to the anchor Tx nodes. The anchor Tx nodes in the UWSNs collects and passes data from all of its sensor nodes to the surface floating nodes. The 2D-UWSN communication is carried out in two different dimensions (i) A horizontal communication link connects each cluster member to its Tx anchor node (ii) A vertical communication link connects the Tx anchor node to the surface buoyant node [26]. Acoustic, optical, and RF communication is opted in 2D-UWSN depending on the type of application and the nature of the environment. The 2D-UWSN can be used in both time-critical and delay-tolerant applications [27; 28; 29]. In 3D-UWSN the sensors nodes are arranged in clusters formations that are mounted at varying depths underwater [30]. As Three communication situations are included in this design. (i) K-means clustering transmission of nodes at dissimilar levels, (ii) Maximum inter cluster transmission, and iii) Anchor buoyant node transmission. Optical, RF and acoustic, communication linkages can be used in all three situations of communication [31]. 4D-UWSN architecture is the combination of 1D-UWSN and 3D-UWSNs that creates a four-dimensional 4D-UWSN.