The bad places stink. Musty. Gassy. Spoiled and rotting.

It's the smell of the swamp. And New Orleans is a swamp now, transformed in just eight days from the funkiest of gems into a wild place, a place of black waters, snakes, and spooky, echoing abandonment. Fires burn throughout the city on the surface of oil-slicked water that reaches -- with its spreading algae -- up to the streetlights in some neighborhoods.

There are entire swaths of New Orleans where no one can go without a boat, or hip waders, or foolish courage. But a few go anyway, searching for stranded pets or stranded neighbors, or both. The city -- the worst parts, at least, the deeply flooded east -- is best approached by water.

On the choppy surface of Pontchartrain, the giant lake that poured into the streets with such persisting ferocity, New Orleans looks like a walled medieval city. The huge levees built to keep water out now keep water in.

Edging along the giant lake's shore and poking through myriad canals reveal a netherworld of destruction and vigilantism in some of the city's toughest-to-reach sectors. To the west, a man with a shotgun guarded condominiums at the shredded Orleans Marina. Farther down the shore, a stockbroker slogged through waist-high water, carrying a whimpering pit bull. Way out east, a Catholic-Buddhist-transcendentalist prayed at an altar and took instructions from her long-dead father.

At a boat launch just west of the city, Mike Fitzpatrick wanted what everyone here wanted: a boat ride to get to his guns. He was lucky. He hopped into a little flatboat with a small group of reporters and pointed down the shore toward the smoldering Orleans Marina, where his cache of weapons lay hidden.

The ride took him past the Southern Yacht Club, on the city's western edge. It is charred, a blackened skeleton, overlooking a point pushing into Lake Pontchartrain where New Orleans teenagers would go to make out, using the code words that they were "off to watch the submarine races." Fitzpatrick, a riverboat pilot who people around here call a "Y'at" -- shorthand for the city's signature greeting, "Where y'at?" -- shook his head and grabbed for a ringing cell phone.

"It sunk?" he said to a fellow boat owner, floating past sailboats tossed onto decks and laid out like fallen dominoes. "Was it insured? Ah, good."

Across the marina from Fitzpatrick's place, a 30-foot yacht perched perfectly on top of pilings, 10 feet above the waterline. It was an incredible sight. A storm that treated New Orleans so roughly seemed to lift this boat into the air and then put it down with the most gentle touch -- barely harmed.

Not far away, heavy helicopters ferrying 7,000-pound duffel bags full of sand thundered down to the 17th Street Canal -- the great villain of Hurricane Katrina, with its 500 feet of broken levee that allowed thousands of homes to be engulfed before the gap was closed Monday.

Watching from a nearby bridge, Kenny Crumholt, a resident engineer with the Army Corps of Engineers, remembered the first sandbags dropped in days ago, the ones that disappeared beneath the surface, demonstrating the depth of the chasm. "We would drop them and they would sink," Crumholt said. "We were getting aggravated."

Along the canal, the fortunate -- the ones who live on the opposite side of the levee break, the ones whose houses are dry -- have built ladders out of old crates to watch the progress, or lack thereof. "If this would have broke on our side, it would have been all over for us," Sherry Blue said.

About a mile down shore, Renee Pastor -- a fast-talking redhead with a stubborn streak -- floated into the Orleans Outfall Canal on a rumbling powerboat for a rescue mission. She had to save her dogs left behind by an evacuating pet sitter, and she had to find Mr. McCobb, an elderly neighbor gone missing.

Pastor brought help -- serious help. Dale Coon, sunburned and sporting a barbed-wire tattoo on his left arm, stepped out of her boat and climbed up the canal levee, stuffing a .38 Special and .357 magnum into his pants front.

"That's one good thing about being from a family of rednecks," Pastor said. "Everybody's got guns."

After Pastor and Coon waded through a street turned pond to collect her bulldog, Chance, and her chubby Labrador, Max, they set off to find Mr. McCobb. Pastor's neighborhood of million-dollar homes, all backing up to a private park, was covered with foul, inky water. The rotten-egg stench of broken gas mains scented their slog past the oil fire, the house burned to its foundation, the submerged park, the BMW flooded to its rooftop.

Her house -- just renovated with pricey Asian flourishes -- sits on a virtual island neighborhood called Lake Vista, bounded on three sides by Lake Pontchartrain, Bayou St. John and the Orleans Canal. Pastor carried a slip of paper with an address, but navigating streets she once knew so well became a series of stops and starts. The water contorted all perceptions, toyed with her sense of direction.

"Go left, big ol' snake there," Coon called out.

The little rescue party, wearing the post-Katrina fashion statement of plastic pants with bootees that go over their shoes and suspenders, veered quickly. Water moccasins, among the deadliest of snakes, have been spotted in the city, and no one wanted to wait around to see if this was one of them.

The snake detour took them to a little white, wooden house. Pastor made everyone stop. "He might be hiding in there with a gun," she said.

"Hellooooo! We're here to help you. Don't shoot," she said, easing toward the house.

Coon turned detective.

"He ain't gone," he said. "Look."

In the driveway lay a survivalist's arsenal: two transistor radios, a cell phone, a half-empty bottle of Napa Valley zinfandel, tobacco, a pipe and some blackberry soda.

Coon stooped and picked up four shiny cylinders: shells from a .22 magnum. "Ain't been long since this been shot," he said, drawing a deep whiff. "He ain't gone. He's hiding. Freaked out. Scared."

Pastor yelled out again: "I'm coming in. Don't shoot. Don't shoot."

Inside the house, her calls went unanswered. Two guns and a pile of knives sat on a table by the door. But no Mr. McCobb.

Dale Coon and Renee Pastor traveled by powerboat to rescue one of her dogs.