Chad Seymour, Hawai'i's top-ranked entry, said the Xterra is "drastically different from Kona," where the Ironman Triathlon World Championship was completed last weekend.

The course consists of a 1.5-kilometer ocean swim at Wailea Beach, followed by a 32-kilometer mountain bike up and down the slopes of Haleakala, and then an 8.5-kilometer trail run from lower Haleakala to the Wailea Marriott.

"Of all the triathlons I do, this is probably my favorite," said Seymour, 22. "It's a real tough course; very challenging. At the same time, you can't ask for a better place to hold a race."

There are 75 professionals vying for the overall titles — 50 men and 25 women. The men's and women's champion will each receive $25,000.

Seymour is the only professional from Hawai'i in the field.

Last year's champions, Eneko Llanos from Spain and Melanie McQuaid from Canada, are back to defend their titles.

Other top contenders in the men's race include Olivier Marceau and Sylvain Dodet from France, Conrad Stoltz from South Africa and Josiah Middaugh of Colorado.

Other top contenders in the women's race include Jamie Whitmore from California and Candy Angle of Massachusetts.

The rest of the competitors are amateurs, including more than 150 from Hawai'i.

Among them is Lorenn Walker of O'ahu's North Shore. She has entered five Xterra Championship races, and won her age group four times.

"It's just a beautiful race; it's a striking view when you come down the bike ride — something I get to see once a year," Walker said. "What I also love about Xterra is that they write your age on the back of your calf. I love that because I can see exactly how old the people are in front of me. It's so fun to try and pass all the younger numbers."

Approximately 40 of the entries are going for the Hawaiian Airlines Double. To qualify for the Double, a triathlete must complete the Ironman and the Xterra triathlons (which are held eight days apart). The fastest combined time will receive a $2,500 prize.

The race is scheduled to begin at 9 a.m.; first finishers are expected to reach the Wailea Marriott around 11:30 a.m.