If there is one constant at the U.S. Open from year to year, it is the difficulty of the rough. But this year's rough at Erin Hills might make the rough at previous tournaments seem tame.

PGA Tour veteran Kevin Na was playing a practice round at Erin Hills and posted a video showing just how much trouble a player will get in if they miss the fairway by more than 3-5 yards.

In the video, Na tosses his ball just three yards past the first cut of rough — which Na says is 3-5 yards wide — and into the tall fescue, which is on every hole. Na is now 6-8 yards from the fairway and you can't even see the ball.

Na took one swing with his caddie in the background saying, "no chance." The ball didn't move.

Na took a second swing. This time, not only did the ball not go anywhere, but Na actually lost his ball!

Here is the video, with the caption, "Erin Hills is a great design course but the fescue is almost unplayable. BTW never found the ball. So don't hit it in there lol. straight hitters have a chance!"

SEE ALSO: The best pictures from the Stanley Cup Final

Join the conversation about this story »

NOW WATCH: WATCH: LeBron James responds after his LA home was vandalized with a racial slur