A boy at the beach runs through the surf towards three other people who are already in the water.
A boy can't swim so he didn't go to the beach with his family.
If the boy didn't go to the beach he cannot be at the beach.
The boy can't swim and didn't go to the beach so there is no way he could be running towards people in the water.
The boy either stayed at home or went to the beach with his family.