USA Climbing Championships

It's billed as the biggest gathering of rock stars in the country, but you won't find an electric guitar in the crowd. Tomorrow marks the start of the USA Climbing association's 2005 National Championship, a three-day competition in which more than 400 junior climbers ages 9 to 19 clip on carabineers and take cracks at scaling jagged, 45-foot walls. MetroRock in Everett, Boston's newest and biggest indoor rock-climbing gym, will host this year's amateur championships, which have never been held in Massachusetts.

''We've got over 17,000 square feet of climbing surfaces and a mile of rope hanging from the walls," said manager Pat Enright. The gigantic, cave-like climbing walls look as if they were plucked from Middle Earth. ''It will be the single-largest climbing event in the country this year."

With as many as eight climbers ascending at once, spectators should get their fill of tumbles and triumphs as they beat the heat in air-conditioned comfort. As baby-faced climbers reach dizzying heights, excitement is just about guaranteed, organizers say. ''We were in New Mexico two weeks ago and people were on their feet cheering for these kids," said Anne-Worley Bauknight, executive director of USA Climbing, the national governing body for rock climbers based in Boulder, Colo. Entrants say the competition is traditionally friendly, but the challenges climbers face are anything but: Protrusions the size of king-size beds will force the best to climb with their backs to the ground.

''Usually the tips of your fingers and your toes are the only thing touching the rock," said Zeb Engberg, 18, of Westborough, who's vying for one of 30 spots on a co-ed national team that will compete in Beijing this fall. ''You get used to it, I guess."

Passes are $15 and are good for all three days of competition. Finals in both speed and technique climbing will be held Sunday. See www.usaclimbing.org or www.metrorock.com for more details.