LISBON — All that's needed is a pumpkin, a flashlight, a knife, a wet suit, an air tank and a little creativity.

Six scuba divers carved jack-o'-lanterns more than 10 feet below the St. Lawrence River's surface Saturday evening near the Lisbon Beach and Campground. The inaugural underwater pumpkin carving contest had designs ranging from a small hole to a vampire.

"I planned it out ahead of time," said Potsdam resident Christopher F. Lenney, claiming top honors with a skull and crossbones design. "I wanted to stay with a water or pirate theme."

None of the participants had ever carved a pumpkin underwater, just at the kitchen table. The first lesson was quickly learned under the moonlight — carving is made more challenging because pumpkins are naturally buoyant.

"The trick is you have to put weight inside it," said John Ashley, co-owner of Blue Fin Diving, Route 68. "The challenge is keeping it on the bottom without letting it float to the surface."

One carve-off rule was that the pumpkin couldn't have any cuts in it before the descent. No preparation could be done on land. Removing the top, pulp and seeds had to be done underwater.

"Once I got it opened up and the air out of it, carving the pumpkin was much easier," Canton resident James P. Yaeger said.

The chuckles from shore were constant shortly after the contest started as several spectators watched divers attempt to sink the pumpkins with varying amounts of success.

"It's so funny to watch," Mr. Ashley said.

Some of the divers came prepared with diving belts, mesh bags and extra weights. A few scoured the river bottom for large rocks to sink themselves, along with the pumpkin.

Mr. Lenney sliced and pared his large pumpkin while keeping it weighted down with rocks inside a mesh bag. He spent more than an hour underwater carving his winning design, which earned him a pair of fins.

"It was definitely a challenge," he said.

The contestants shared their underwater carving experiences afterward with a campfire, complete with hot dogs, doughnuts and drinks, next to the campground on the McMahon property.

"We hope to make this an annual event," Mr. Ashley said. "This was a good start. We hope to have more people participating next year."