Underwater Acoustic Sensor Network (UASN) is based on the sensory elements which detect the environmental conditions of submerged region and transmit the information through acoustic waves at the sink node placed on top of the water. All these sensory elements are battery operated just like the Terrestrial Wireless Sensor Network (TWSN). However, these nodes are not stationary, unlike the nodes in TWSN. Thus, routing with limited energy and ever-changing topology decreases the reliability of the network and increases the chances of Void existence. This research paper focuses on the comparative analysis by critically reviewing of some of the state-of-the-art routing protocols which are based on the effective usability of the limited energy resource, reliability of the network and Void occurrence issues. An analytical method is employed to examine the strengths and shortcomings of existing routing protocols, with a specific emphasis on the identified difficulties. It provides a solid foundation related to UASN routing protocols which are primarily designed with a focus on resolving issues such as limited energy, low reliability and high chances of void occurrence. The contribution of this comparative study helps the research partners from academy and industry which are new to this field of study and would like to contribute.