This book is intended to meet the needs of those who seek to develop control systems for ROVs when there is no model available during the initial design stage. The modeling, simulation and application of marine vehicles like underwater robotic vehicles (URVs) are multidisciplinary, and combine mathematical aspects from various engineering disciplines. URVs such as remotely operated vehicle (ROVs) are used for a wide range of applications such as exploring the extreme depths of our ocean, where a hard-wired link is still required. Most ROVs operate in extreme environments with uncertainties in the model prior to control system design. However, the method involved extensive testing before the system model could be used for any control actions. It has been found that the range of error can be extensive and uncertain in actual, continuously varying conditions.  Hence, it is important to address the problem of reliance on model testing using different modeling approaches. In this book, approaches such as WAMIT, ANSYS-CFX, STAR CCM+, MATLAB and Simulink are used to model parameters for ROVs. A few benchmark models are provided, allowing researchers and students to explore and test different control schemes. Given its scope, the book offers a valuable reference guide for postgraduate and undergraduate students engaged in modeling and simulation for ROV control.