They call it the Ball Washer. The 18th hole at the Golf Club of Houston (GCoH) is one of the most nightmarish in the country, 488 yards of unadulterated terror. It stumps amateurs and hot-shots alike, routinely ranking as one of the dozen most difficult holes on the entire Professional Golf Association (PGA) circuit. J.B. Holmes—who won the Shell Houston Open here in 2015, expertly navigating the 18th twice during a three-man playoff—has called it “scary and terrifying.” Other pros have described it as “brutal” and “borderline ridiculous.”

Trouble starts with a treacherous tee shot. There are deep sand traps hugging the fairway, 55 yards long, positioned exactly where a wayward drive is most likely to land. On the other side lies a foreboding lake which cascades all the way to the green, and which will swallow any shots that drift even marginally. Reese McCall, the course’s amiable head pro, can’t imagine how many lost balls are swimming in that water.

Those fortunate enough to avoid hazards off the tee aren’t yet in the clear, as the second shot, even from the fairway, is equally murky. The multi-tiered green is wedged between another large bunker and the northern edge of the lake. Accuracy, especially if the wind is blowing, is paramount. “Land most anywhere over there,” McCall says, pointing to the left-hand slope, “and it flies right off.”

For Greg Muirhead, the devious mind who designed the GCoH, the difficulty of the 18th is a feature, not a bug. “What’s great about the hole is that visually, it all unfolds for you from the tee,” he says. “Everything is apparent. You know where you want to go, and where you don’t want to go.”

From March 27 to April 2, 125,000 spectators will descend on the Golf Club to see if the world’s best can handle the challenge for the Shell Houston Open. Established in 1946, the Open is one of the PGA’s oldest events, with a prize purse of $7 million. The club built its tournament course, which opened down the road from Bush Intercontinental in 2005, specifically to host the annual event. “We’re starting to prep,” McCall tells a visitor on a balmy January afternoon. “Everything we do, for the next two months, is basically prep for the Shell.”

Thirty-three Masters invitees played here last year, including household names like Jordan Spieth, Rickie Fowler and Phil Mickelson. The 2017 competitors will be set a week before the first round. They’ll all knock it around the 7,422-yard course, over the wetlands and past the cypress trees. And when they arrive at the 18th, they’ll face the same harrowing task that Houstonians have come to dread.

McCall hops in his golf cart and motors down the cart path, pulling up alongside a fairway sand trap. Trailing him is a duffer sneaking in a weekday round by himself, mid-range iron in hand. The breeze gusts at the exact wrong moment, and just as McCall warned, the man’s approach nicks the front of the green, spins back slowly, drifts off the putting surface, and sinks into a gulley. A decent shot, completely wasted. He shakes his head in frustration.

The Ball Washer strikes again.