Jeff Probst, the amiable host of "Survivor," summed up the 11th season matter-of-factly: It's the toughest. Period.

"Survivor: Guatemala -- The Maya Empire," set among 2,500-year-old ruins, lush rain forest and a muddy lake, includes some of the most rigorous challenges ever. The 16 contestants also contend with 120-degree temperatures, mind-sapping humidity, mosquitoes, snakes, crocodile-infested waters and -- most treacherous of all -- each other.

		'Survivor: Guatemala -- The Maya Empire' When: Tonight at 8 on CBS.

"We hadn't done tough-tough-tough before," Probst said. He said that although "Survivor: Africa" contestants will want to defend their title of having the toughest "Survivor" conditions ever, especially because they had virtually no water, "Survivor: Guatemala" is more brutal.

The show opens with an 11-mile hike that has some of the fittest competitors on their knees and on their backs, gasping and throwing up from exhaustion. With most of the contestants in their early 20s, this may be the youngest group ever.

An older competitor, Margaret Bobonich of Chardon, Ohio, a family nurse practitioner, is even concerned about some life-threatening health conditions on her tribe in the opening episode, Probst said.

He confirmed a plot twist that brings back two former "Survivor" contestants on competing teams. The Survivor Fever Web site says they are Bobby Jon Drinkard and Stephenie LaGrossa, two favorites from last season's "Survivor: Palau."

Probst wouldn't confirm, although he said audiences had "probably seen enough of Rob and Amber," referring to Rob Mariano and Amber Brkich, who got married after "Survivor: All Stars" and have become television staples since then.

Brkich, from Beaver County, won the $1 million prize for that season, as did Jenna Morasca of Bridgeville for "Survivor: Amazon." Ian Rosenberger of Economy finished in third place in Palau last season, essentially giving up the game and handing the $1 million to the eventual winner, Tom Westman. (Dolly Neely of Mercer County was the second casualty of "Survivor: Vanuatu.")

In Guatemala, Western Pennsylvania has its fifth "Survivor" contender in Rafe Judkins, 22, of Kilbuck.

On a video on the CBS Web site, Judkins describes himself as "a gay, Mormon, Ivy League-grad wilderness guide." A recent graduate of Brown University, he had a concentration in biology and anthropology. He attended Sewickley Academy for 14 years, and he has been to all 50 states and to 14 countries.

Probst said Judkins is "very understated, has a tremendous personality and is very likable. People will really get behind Rafe. He's gay. He's bright. He's really studied 'Survivor.' He had studied Mayan culture right before the show, even though he didn't know 'Survivor' was headed there, and he has a leg up."

On the CBS Web site video, Judkins says: "They're going to look at me and see that I'm friendly and that I'm this gay guy -- what damage can he do to anyone? They won't expect that I will probably be the smartest person out there, that I have a ton of outdoors experience, that I really know how to play this game." He's the son of Ren and Lani Judkins.

Another competitor is Gary Hogeboom, a former NFL player who tried to conceal his identity from the other players. He told fellow players that his name was Gary Hawkins, Probst says, but another contestant, Danni Boatwright, a sports radio talk show host from Kansas, recognized him. Probst declined to say whether Boatwright "outed" Hogeboom, although he praised both players' savvy.

"This is definitely a season in which teams need the strongest players to survive." Probst has spoken.