NIAGARA FALLS -- The Horseshoe Falls took a back seat Thursday morning when tourists on the

Maid of the Mist discovered they had walked onto the set of the NBC comedy "The Office."

Actor John Krasinski and actress Jenna Fischer stood at the front of the famous boat

attraction as they filmed a scene for an upcoming episode set in Niagara Falls, where their

characters -- Pam Beesly and Jim Halpert -- finally tie the knot.

The cast and crew and about two dozen extras took two 30-minute rides through the swirling

waters below the falls as they shot and reshot what could become a crucial scene in the show's

fourth episode this season.

Above them, on the boat's second-floor deck, tourists who had come from as far as Australia

and Japan to see the waterfalls got a bird's-eye view of the two television stars at work.

"We come up here one time, and we get on the Maid of the Mist and they're shooting a show,"

said Lynn Bryant, a milk delivery driver from Hampton, Va.

Like the time and location of Thursday's production, details of the wedding of Jim and Pam,

the fictional Dunder Mifflin employees, have been kept a secret.

But Fischer did wear a white empire-waist wedding gown with beaded trim, and Krasinski wore a

black tuxedo with a boutonniere of two white flowers during their Maid of the Mist ride.

The pair also wore blue Maid of the Mist slickers, but took them off as they neared the falls.

Heavy mist soaked their clothes and left them dripping wet throughout several takes as the

boat rocked in the water.

"None of us expected this whatsoever. The actors were completely drenched," said Randy

Cordray, producer. "It was like standing in your backyard and having someone spray a hose

right in your face, but John and Jenna played their scene beautifully, and the troupers that

they are, they powered through it."

Cordray said staff from the show twice scouted the location by taking Maid of the Mist rides

three weeks ago and again on Wednesday, but did not encounter the amount of water that sprayed

over the actors Thursday morning.

"Once the actors got wet, there's nothing you can do about it," Cordray said. "So we just

stayed wet, and we took another boat ride, and we went around again, and we played it wet for

the second go-round."

Cordray also played a boat captain in the episode.

The shooting took place on regularly scheduled tours of the Maid of the Mist.

Filming the show aboard the boat was a challenge for the cast and crew, which typically shoots

on a studio set in Los Angeles. That meant abandoning the high-definition cameras the crew

typically uses and instead using a 16mm camera with a spinning device that keeps water

droplets off the lens.

Fischer's hair and makeup also were factors under the falls.

"We had to think of waterproof mascara, anything that wasn't going to run, while still keeping

them fresh-faced," said Laverne Caracuzzi-Milazzo, head makeup artist for "The Office."

"Obviously due to this particular episode, we still needed to keep them looking good at all

times."

The characters Pam and Jim, whose office romance has been a focal point on "The Office," were

engaged last season and found out in the season finale that she was pregnant.

Cordray said the show's head writers, Greg Daniels and Paul Lieberstein, chose the American

side of the falls for the wedding over its Canadian counterpart.

"It's the most romantic spot in America," Cordray said. "They wanted an iconic natural

location for the wedding to take place in, and what a better spot?"

Fischer and Krasinski also shot a scene outside the Red Coach Inn -- renamed the Statler Falls

Hotel for the episode -- in which Fischer carries her wedding dress into the hotel as

Krasinski talks to the camera in the show's mockumentary style.

About 30 local residents served as extras in the filming. Some stood in rain ponchos on the

Maid of the Mist, while others walked by the hotel in the background. "It's like [the movie]

"Groundhog Day,' because we had to do the scene like eight or nine times," said Jackie Flynn,

a Buffalo resident and teacher at Starpoint Middle School, who was an extra. "But it's one of

my favorite shows."

Cordray said most of the episode was shot at inside locations in Los Angeles, including a

restaurant and a chapel.

The episode is scheduled to air Oct. 8 as an hourlong special, said Tim Clark, Buffalo Niagara

film commissioner.

A few clues to the episode's plot were visible to the public Thursday, but producers were mum

on the details. Fischer wore white boots with her wedding gown, and Krasinski's black tie was

cut in half. There was also a long kiss between the two on the boat.

"Our show unfolds to our viewers like magic, and you don't want to peel back the layers behind

the curtain. So we're very secretive about the nature of our story lines," Cordray said. "All

I can really say is that the wedding does happen in Niagara Falls, and Jim and Pam decide that

they would really like to get closer to the waterfall, and so to do that, they take a ride on

the Maid of the Mist."

The shooting -- which the crew tried to keep secret until Thursday by dubbing it the "Chandler

project" -- drew a small crowd of in-the-know spectators who bought tickets for the Maid of

the Mist ride.

Others arrived just to see the falls and got an extra treat.

"That's fantastic," said Australian resident Samantha Pesaturo, who visited the falls with her

aunt and happened upon the set. "We had no idea. It's an added bonus."