In the movie The Hunger Games: Catching Fire, Beetee (played by Jeffrey Wright) comes up with the plan to wrap a wire around the "Lightning Tree", and plant the other end of the wire in the water at the pond (to electrocute their opponents). The group leaves the pond and hikes quite a distance to the tree. They wrap the wire around the tree and then send Katniss back to the beach with the other end of the wire.
So, since they start at the beach, why didn't they leave one end there, rather than repeating the entire hike all over again?
I understand they wanted to separate Katniss from the group.