The research aims to infer electrical activity in the brain to determine the active side of the brain during the performance of the skill of mental relaxation, where the researcher used the descriptive method (case study) due to its appropriateness of the nature and objectives of the research, the research sample was selected in the deliberate manner of divers enrolled in the International Diving Organization in Misralam (2021/2022 AD) and the number of (nine) divers, The researcher used electroencephalograph , one of the technological devices used in neuropsychology to study the electrical planning of the brain, and the researcher concluded that the active dominant side of most diving players is the left side, and recommends further scientific research in the field of neuropsychology applications in the field of sports due to the importance of this scientific research in the disciplines of The researcher concluded that the dominant active side of most diving players is the left side