The sweet-voiced young boys and deep-voiced older boys sang Christmas carols and a Hanukkah medley. All the while their bodies swayed like ripples in the Red Sea.

The 150 members of the Keystone State Boychoir weren't just delivering a holiday concert yesterday at First Presbyterian Church in Germantown. They were warming up their voices for a trip that truly requires warming.

They're going to sing in Antarctica.

On Thursday, the choir leaves on a concert tour to Chile and Antarctica. The one-day Antarctica excursion, where they will sing to a multinational audience of researchers stationed on King George Island, will give the choir the distinction of having performed on every continent.

What significance does that hold for 18-year-old Stuart Pasch of Lower Gwynedd, who has been in the choir since its founding?

"First of all, it's bragging rights," he said.

Second of all, it's one more trip for him and the others that is sure to be filled with laughter, life lessons, and unexpected events with the choir he loves.

The Antarctica performance is part of the group's trip to Chile to celebrate that country's 200th anniversary.

Associate music director Steven Fisher had considered taking a tour there ever since a Chilean American friend described the beauty and culture of his homeland.

Antarctica was added to the itinerary because, comparably speaking, it was a short hop (about three hours) by plane from a town in Chile where the choir is to perform and because it was the last continent the group needed to boast it had collected the full set.

Fisher and music director Joseph Fitzmartin founded the choir in 2001, a year after meeting while working for the better-known Philadelphia Boys Choir & Chorale, Fisher said. The two musicians shared a belief that choral singers should use their entire bodies and their emotions while performing, not stand motionless.

"I've always just felt that if choral music is to thrive in today's world, it should be seen and felt as well as heard," Fisher said, explaining why he and Fitzmartin began the choir.

"We basically ask them to let their bodies sing with their voices," he said.

Pasch, standing in the last row, tilted his face toward the heavens as he sang. In the front, a young boy opened his mouth so wide on long notes that the bottom half of his face seemed to disappear.

The members live throughout the Philadelphia region and have a variety of backgrounds. They range in age from 8 to 18.

One of Fisher's favorite stories illustrating the choir's diversity comes from a plane ride on its first overseas trip, to South Africa in 2001.

A young choir member from an impoverished Camden family was playing cards with a boy from one of the area's wealthiest families.

The Camden youngster, enjoying his first flight, remarked, "This is so awesome," while his wealthy friend noted how cramped it was in coach seating.

"The beauty of that is that music is the great equalizer," Fisher said. "A choir like ours brings kids together."

The choir has brought Pasch together with Matthew Bedenko, a 12-year-old from Wallingford, who is making his first tour with the choir.

Bedenko said he was mentally prepared for the adventure, which means he has no expectations except that Antarctica will be cold.

"I don't think it will affect my singing," Bedenko said.

No expectations is the best approach for these trips, the veteran Pasch, who will leave the choir in June, said yesterday between songs. He told of missed planes and trains, of unexpectedly having to sing to royalty (the prince of Monaco) in T-shirts instead of the choir's forest-green suitcoats and matching ties.

The biggest lesson of his nine choir years is this, Pasch says sagely: "Stuff goes right, but it doesn't go right all the time. You learn to keep your head up and go with it."

Contact staff writer Carolyn Davis at 215-854-4214 or cdavis@phillynews.com.