Underwater robotics is a branch of robotics. Underwater robots can be autonomous, or they can be remotely operated. This is an emerging science, which has become more popular with evolving technology. There are many applications of underwater robotics such as scientific exploration, military use, and hobbies. Besides capability of swimming an underwater robot also has multi DOF manipulators and end effectors on these arms of various types to perform underwater tasks such as construction, salvage, rescue and repair. They can also help in collecting items that are deeply submerged inside the sea, used by the military and scientists mostly.