The woman is parasailing, holding onto a harness and being pulled through the sky.  
The boy is wakeboarding, holding onto a handle and being pulled across the lake.  
The athlete is kite surfing, holding onto lines and being pulled over the waves.  
The surfer is bodysurfing, holding onto a board and being propelled by the current.  
The skier is being towed, holding onto a rope and being pulled down the snowy slope.