A man stands on one side of a river, his dog on the other. The man calls his dog, who immediately crosses the river without getting wet and without using a bridge or a boat.
How did the dog do it? (There are many answers to this question)
Could it be that the river is frozen? Because then the dog would not get wet and could walk across easily if the river is thick enough.
The river is seasonal and currently dry. Or the dog is on the other side of a sharp bend in the river and can just walk around. Or the river is narrow and the dog can jump over. Or the river is underground. Or the dog is wearing waders.