This is because, in case, of emergencies or unpredictable accidents (boat engine failures, drowning, unpredictable attacks from water animals example for example sharks bites,) common to water activity medium , others members of the group can seek for aid or helps. For example from life guards or from emergency department outside the environments to save an endangered life or provide needed first aids measures before help arrives.
This ensured safety of lives and prevention deaths or fatal injuries.
