KIAWAH ISLAND, S.C. — Everyone has noticed. Some before others. 

But every player who’s competing in the PGA Championship, which begins with Thursday’s opening round on Kiawah Island’s daunting Ocean Course, is well aware that this layout (measuring more than 7,800 yards from the tips) is the longest in major championship history. 

Add in the wind off the Atlantic Ocean, and what you are guaranteed to have this week are a lot of headaches and scores high enough that you may think they’re misprints for professional golfers. 

“I noticed it last week when someone sent me a scorecard and I saw that the back nine was 4,000 yards,’’ Justin Thomas said. “I think I actually laughed out loud when I saw it because I was looking at the numbers, [thinking,] ‘They can’t possibly play it that long unless they get a day where there’s absolutely no wind.’ ’’ 

That’s not going to happen. While there are not outlandish, batten-down-the-hatches winds in the forecast, there will be enough to affect a lot of golf shots. 

For most of the practice rounds, the wind has made the final five holes borderline treacherous. Those holes have made players dust off their mid to long irons that haven’t been used a lot in recent years as the players all get longer and eat up most golf courses. 

While professional golf has sadly morphed into driver, then 8 or 9 iron into par 5s, this week will be a throwback, making the players hit (gasp) long irons into par-4s. 

“If the wind blows this way for the rest of the week, it’s going to be a battle to just get in the clubhouse,’’ Adam Scott said. 

“I’m not used to hitting a lot of long irons, mostly into par-5s, not par-4s, so I think that gave me a little bit of a taste what it could be like this week,’’ said Tony Finau, who’s one of the longest hitters in the game. 

Jon Rahm, another one of the game’s big hitters, said he “seriously hopes’’ the PGA doesn’t keep the tees back all week (which it won’t) “for the sake of our sanity.’’ 

The par-3 17th hole, which sits hard by the Atlantic and features a tee shot over a large body of water with no safe bail-out places to land, is the star of the show in the home stretch. 

Player after player, during pretournament interviews this week, have told tales of woe about their experiences on the 17th — and those were merely in practice rounds. 

For the TV viewer at home, sit back and enjoy watching the players’ knees knocking as they stand on the 17th tee — particularly on Sunday. If the final-round leaderboard is bunched, players will be squeezing their clubs extra tightly. 

“Seventeen is the ultimate test of nerve, really,’’ Scott said. “It’s a long par-3 over water. I don’t know how holes get more difficult than that, and [in the practice rounds] it’s [been] straight into the wind. I’ve been hitting 4-irons and 7-woods and briefly discussed hitting a soft 3-wood in to see how that feels. 

“I think if it is into the wind, you’re going to see guys wearing out the left side. There are some bunkers and then I think we could see guys going even further left. It’s not great, but it’s a lot better than the water. It could be a decider for the whole event this week.’’ 

Defending PGA champion Collin Morikawa said he was hitting 5-woods at 17 in the practice rounds. 

“There’s nowhere to bail,’’ he said. “Usually, you just kind of play away from the hazard, but it’s hard to play short left because you still have water, you still have wind and you only have about 15, 20 yards. Are you just playing center of the green? Are you playing at the bunker? It all depends on the wind. 

“I think coming down on Sunday … how people are going to have momentum is those last couple holes are going to be huge.’’ 

Abraham Ancer called 17 “definitely a hole that can change the complete championship.’’ 

“There’s going to be a lot of crazy stuff going on on that hole, which makes this exciting,’’ Ancer said. 

Thomas, issuing a passive-aggressive challenge to the PGA of America, said he doesn’t believe the course will be playable with wind if they set the tees up at the tips. 

“Unless the PGA wants seven-hour rounds,’’ he said, “I wouldn’t advise it.’’