Sitting on the beach Wang could see as far as several miles covered with sand, you the left and right. This already showed him that the river was indeed too long, considering he couldn't see the end or even the intersection with other streams.
Starting in the distance, he couldn't help but frown because he realized something even scarier. Which was that there were no footprints on the sand.
Regardless of the situation, this was a God water source being a river, it is to be expected for monsters to drink this water and thus the number of footprints on the shoreline should be more.
Even when he touched the ground he was sitting on, he could feel some of it was sturdy, but when force was exerted it still left behind an imprint.
It was thus surprising that he couldn't even see any footprints in the sand to the edge. His eyesight was indeed good and he could see farther than most.