Tourists know downtown Charleston's Waterfront Park for its picturesque panorama of the region's best features -- Fort Sumter, the Ravenel Bridge and river-buffering marshland.

Thank goodness the view draws them to look out over the harbor, not down at the ribbons of trash that wash up along the shore.

Area environmentalists say the Waterfront Park marshland is perhaps the dirtiest spot along Charleston's shoreline, littered with trash from boats in the busy waterways and downtown visitors who stroll the peninsula's outline.

On Saturday, a swarm of volunteers stepped into that scenic view, wading through waist-high marsh grass to pick up the trash for the 22nd annual Beach Sweep/River Sweep. Roughly 2,300 people in the Charleston area signed up to participate in the statewide event, which was organized by the S.C. Sea Grant Consortium and the S.C. Department of Natural Resources.

Littering is illegal. But without a local, state or federal agency in charge of actually cleaning up debris, voluntary events are one of the few ways that trash gets picked from the region's coastline.

"This whole thing about litter pickup tends to fall on nonprofit organizations and volunteers who are filling a need," said Sue Schweikart, who helped organize the coastal region's cleanup.

At Waterfront Park, volunteers squished around in the soft marshland, bending over into the bright green patches and popping back up with mud-caked debris.

"You really can't see in this stuff," said Chris Robinson, 32, of Summerville, parting strands of marsh grass.

Inside those clumps of grasses festered an overpowering odor. David Gilbert, 33, of James Island said it smelled like over-salted eggs.

Nearby, College of Charleston senior Andrea DeSantis watched her colleague untangle a stylish camouflage trucker hat from some bushes.

"That's cool but can you wash it first?" she said with a broken canoe paddle tucked under her arm.

Each trash-picker was instructed to call out what they retrieved -- "tennis ball!" "bike tire!" "flip-flop!" "soccer ball!" -- so volunteers on the sidelines could write it down.

The long list of debris helps organizers keep track of how much stuff is strained from the waterways.

Last year, volunteers across the state picked up 45.5 tons of trash.

Organizers won't know for a few days how much debris was collected on Saturday.

Local organizer Susan Ferris Hill also keeps a list of unusual debris for her own amusement. Over the years, volunteers have picked up shattered TV sets, a set of crutches, a bottle of urine and a grill (as in the decorative tooth covering, not the outdoor cooker.)

"Most of the debris we pick up has fallen from a human hand," Ferris Hill said.

Most of the trash fits into three categories: boating, food- and drink-related, and cigarette butts. But it's not quite clear whether the litterbugs acted maliciously.

Some stuff simply falls out of boats, washes away in an unexpected wave or gets picked up by a breeze. Volunteers always have found items that seemed unintentionally trashed: bikini bottoms, cell phones, a tooth brush.

Organizers dispatched a team of trash-pickers to the West Ashley Greenway, an eight-mile recreational path and a seemingly unlikely spot for trash.

"It's not actually coming from the joggers and bikers," Schweikart said. "It's coming from Savannah Highway, probably after falling off a truck."

There are years when cleanup crews in certain areas have reported unusual amounts of things like rope or fireworks, Schweikart said.

Saturday's event, she said, recorded nothing unusual. Certainly nothing as exciting as the 2008 cleanup on Sullivan's Island when a shiny piece of rubber caught a local high school student's attention.

"She leaned over to pick it up, and it turned out to be an alligator's tail," Ferris Hill said.

The four-footgator, which was nesting comfortably under a bed of sea grasses and bushes, was startled but didn't attack.

On Saturday, the Waterfront Park volunteers' most interesting bit of trash was a two-pound package of meat, which doesn't quite measure up to last year's best find: a bottled love letter from a young girl who was enamoured by Harry Potter star Daniel Radcliffe.

Three years ago, trash-pickers near the ports authority terminal found a green glass bottle -- corked with a rolled up piece of paper inside -- from a fifth grade class in Harleyville in the 1980s. Students had written down what they wanted to be when they grew up.

Edward Evans, a West Ashley resident who usually organizes the Waterfront Park cleanup, said he tried to contact the class's teacher but never heard back.

"Some of them wanted to be doctors," he said, wondering aloud what happened to those kids.

Reach Katy Stech at 937-5549.