SODDY-DAISY, Tenn. — In the depths of the Little Possum Gorge, a footpath strewn with the tools that built it suddenly emerges through a forest of hemlock and magnolia to a breathtaking waterfall.

The treacherous falls, dubbed "Imodium" after the anti-diarrhea drug by those adventurers whom it has scared witless, was once known only to the most daring of kayakers willing to plunge down the 25-foot drop.

With every clank, though, a team of volunteers cobbles together the latest piece of a rocky pathway leading to a shallow pool beneath the rapids, part of a 40-mile trail they're building just north of Tennessee's border with Georgia.

The stretch is a lynchpin in the ambitious Great Eastern Trail, a path of about 1,700 miles envisioned by hiking enthusiasts to someday string together a vast network of existing trails and link the Florida-Alabama border to New York's Finger Lakes.

Planners hope that eventually it could serve as a foundation of a 10,000-mile network of paths spanning from south Florida to Maine, from Virginia to North Dakota. With increased development and sprawl along the East Coast, they believe the timing is right.

"If we don't do it now, it's not going to happen," said Jeffrey Hunter, the American Hiking Society's Southeast trails director.

Hunter is working with local trail groups and volunteers across the nation to build roughly 600 miles of new trail to connect a system of trails already in place. The new trail will largely be constructed on public lands, but occasionally trail groups will have to negotiate the purchase or donation of land.

When finished, the Great Eastern Trail would stretch just west of the Appalachian Trail, the gold standard of the hiking world dreamed up in a 1921 essay by forester Benton MacKaye.

But overuse of that trail has caused litter pileups, trampled plants and crowded campsites, said Alison Bullock, a director with the National Park Service's rivers and trails program who is helping plan the new trail.

"We're trying to provide an alternative," Bullock said. "We want to disperse the recreation. And there are so many gorgeous and undiscovered locales."

The Great Eastern Trail would start at Alabama's southern border, rolling through gentle forest before climbing up clifftop vistas as the path edges north. A ring of old logging roads would stretch the trail through Georgia to Tennessee, where the trail would pass Chattanooga and border river gorges and rocky outcroppings on its way to the mid-Atlantic states.

Through caves and crags, ridges and overlooks, the trail would then scamper through Virginia, Kentucky and West Virginia. It crosses the narrow width of Maryland next, piggybacking on a historic towpath that's probably the trail's easiest segment.

In Pennsylvania, it wanders through thick, dark forests using old logging roads, etching a path through Paddy Mountain on the trail's only tunnel before ending a few miles north just across the New York border.

Other ambitious trail projects promise to span equally vast areas. The Continental Divide Trail will someday stretch from New Mexico to Montana, offering a primitive, backcountry experience for adventurers. New York and North Dakota could eventually be linked by the North Country Trail. And planners hope the Pacific Crest Trail will connect southern California with Washington.

Those trails, however, all enjoy a federal designation — and the government benefits that go along with it. The Great Eastern Trail relies solely on its network of volunteers to craft its pieces together.

"The intent is to get it going the same way we got the Appalachian Trail going — through volunteer efforts. Right now, the entire burden rests on the volunteer," said Tom Johnson, president of the Virginia-based Potomac Appalachian Trail Club.

The Great Eastern Trail was first dreamed up at a 2001 hiking conference, but the actual construction has been a painstakingly slow process.

Johnson's challenge is filling in a 159-mile gap between trails in West Virginia and northern Virginia. Some of the group's 6,500 members will scout possible routes in August and September, when they don't have to slog through thick underbrush or snow to scour the area.

In northwest Georgia, Larry Madden is organizing a group of 50 to finish a hole in the path network. "A few volunteers are getting a lot of the work done, but we've got a long way to go," he said.

Tom Kelliher, the president of Pennsylvania's Mid State Trail Association, has a 30-mile gap in the state's hilly northern region to fill. Teams of volunteers are busy searching for aging logging roads or traces of existing paths, but still, he said, construction could take five to six years.

Warren Devine, the former nuclear engineer who led the trailblazing effort at Little Possum Gorge, has been working for years to craft his leg of the trail.

Scouting out the backwoods, buying the property and negotiating its boundaries alone took years. State archaeologists and biologists have to probe the area, too, to make sure the pathway isn't disrupting artifacts or endangered species.

Building the trail itself takes the constant work of a team of volunteers who, each day, tear up the thick underbrush using giant rakes and painstakingly clear out rocks, roots and organic material to forge a gentle path. The squads can take a week to puzzle rocky outcrops together into a flat pathway, even longer if they're fashioning a staircase.

In a pair of rough work gloves, 51-year-old local locomotive engineer Monty Matney leads four trailblazers, helping them lug rocks to piece together a few steps. On a nearby ledge, Roy Wheeler, a retiree from Cape Coral, Fla., takes a breather as he watches Devine tiptoe out atop the waterfall.

"It's nice to be out here in the wilderness area with a group, instead of just hiking," he said.

Standing atop the cliff overlooking the rapid, Devine lets loose a relieved sigh as he looks at the latest piece of the trail.

"It's going to be there much longer than all the paperwork I grind out," he said, straining over the clanking of the busy volunteers. "The staircase down there is going to last a century.

"It's one of the most rewarding things I've done."