Wireless sensor networks (WSNs), which use radio waves to transmit data from individual sensors, have found widespread application in many disciplines. Coordinated sensing allows continuous tracking of environmental conditions like temperature, humidity, light levels, and gas concentrations at each node. The WSN area is continuously researched and developed. However, many researchers in the academic community and industry are working on WSNs that do not have live sensors to test, creating a need for simulation. Simulation tools reduce deployment costs and time. System simulation tools are often required during the pre-run system configuration phase. Nodes in an Underwater Sensor Network (UWSN) can either operate independently or collect and transmit data to other nodes or mobile stations, depending on their depth. UWSN has several research directions. Deploying complete testbeds with complex network structures, topologies, protocols, and data links to validate new network protocols or algorithms is expensive. Therefore, there is an urgent need for a simulation environment that can depict real underwater scenarios. Many simulation tools are proposed for UWSNs, but selecting the proper one due to the research requirements is very important to validate and interpret the research results. Furthermore, it is essential to see that the test systems' outcomes are sound and meet standard benchmarks. This paper presents a detailed comparison of different WSNs simulators to reduce the time and effort of researchers and application developers.