When people swim in the ocean, the body will release an invisible electrical signal  Researchers have developed a marine invisibility cloak based on this situation  The invisible cloak shields the electrical signals released by the body so that marine life such as sharks cannot be found  People's tracks
Some fish have many cone cells in the retina, which can sensitively feel the subtle light changes in the water
 In this way, people can get close to and observe marine life such as sharks