Turtle Bay, Ko Olina, Koolau and Luana Hills are some of the most beautiful and popular courses in Hawai'i, if not the world. And they're among the most challenging, as well.

Ask 100 golfers which is the most difficult hole on O'ahu and you're likely to get 100 different answers. But there are a handful of holes almost all golfers have come to fear. Here are a few that have been known to cause even 6-handicappers to bury their irons in the fairway and head for the 19th hole early:

Everyone knows the 18th hole at Ko'olau Golf Club is a widowmaker.

Both the drive and the approach must be hammered over a giant ravine, with no relief left or right and 22 bunkers to contend with. But it's teeing off on the first hole in front of a gallery of waiting golf carts that'll make a man out of you, or at least put a couple of hairs on your chest.

First-tee jitters are one thing, but here at Ko'olau where the Ko'olau Mountains rise straight up into ghostly clouds, you're about to grab the dragon by the tail — and everyone wants to see what you'll do with it.

The serpent features three distinct climate zones, winding ravines, extreme elevation changes and views of cascading waterfalls. Oh, and by the way, it's also rated as the toughest course in the nation.

Why play it? Because it's there. A great green beast waiting to be slain.

And remember, you miss a fairway here and it's a jungle ball. There's a reason the pro shop sells bumper stickers that read: "Got Balls?"

KO OLINA GOLF CLUB Location: West O'ahu Course Info: 18 hole — par 72; 6887 yds Course Type: Resort; Ted Robinson design Slope Rating: 135/129/126 Course Rating: 72.3 Visitor Rate: $160 Kama'aina Rate: $70

Ko Olina Golf Club
18th Hole, Par 4

Located at the JW Marriott Ihilani Resort & Spa in West O'ahu, the Ko Olina Golf Club is widely acknowledged as one of O'ahu's premier courses. The 6,800-yard course offers multi-tiered greens, no parallel fairways, exceptional water features and a ProLink color GPS system that helps golfers map the course, estimate yardage and keep score.

Host to the LPGA Tour (1990-1995) and the Senior PGA Tour (1992), one of the course's signature holes (the 8th) has a picturesque waterfall along the left side and a steep two-tiered green guarded by a long sand bunker. But it's the finishing hole at 18 that lures golfers from around the world.

The 403-yard, par-4 hole plays much tougher and longer than it looks. Water features affect both your tee shot and approach shot, and the severely sloped, twotiered green can unexpectedly add to your score.

Advice from the clubhouse: "Pick the right club and pray."

The Turtle Bay Golf and Tennis Resort, located on the North Shore of O'ahu, features two championship golf courses — the Turtle Bay Fazio and the Turtle Bay Palmer.

Turtle Bay Palmer was designed by Arnold Palmer and Ed Seay. There are five sets of tees — in some cases six — to accommodate both average golfers and the best players of the world. The front nine features sand, water, wind and rolling terrain with no trees or shrubs at all. The back nine plays through a forest of ironwood pines and presents a very different feel.

The 17th hole is undoubtedly the course's toughest hole with no less than nine craggy bunkers surrounding the landing area and extending all the way up to the green. What makes this signature hole even more difficult is the green sits on a plateau less than 90 feet from the ocean. You must go long to avoid the traps, but too long and you'll be fishing for your ball in the surf.

If you're hitting most of your fairways and feel ready to hit a near-perfect drive and the best approach shot you ever made, then you still might not be ready for this hole.

Luana Hills is perhaps the most beautiful golf course on O'ahu, a one-of-a-kind creation sculpted by Dye Design in 1994 in the deep valley between Kailua and Waimanalo.

On these high-risk, high-reward links, you must consider such factors as forced carries, heaving bent grass and fairways that slope off into bunkers and ravines. But the course's signature hole, the 11th, is the one you'll remember the most. Called "The Pond," it's set deep in the thick rainforest along a stream, and players must shoot downward from elevated tees, past shooting fountains, to the green.

Only 127 yards from the white tees, the green juts out on a thin peninsula right there in front of you. Yet, even if you manage to visually block out the water, there are two large fountains spraying loudly in the pond to remind you you're playing the ultimate water hole.