I was fine until Spud Mountain appeared on the table. The waitress seemed to struggle with the very weight of the concoction, a bubbling mass of french fries buried in cheddar cheese and chives. When I pierced the top, steam and bacon vaulted upward through the fissure. The only thing missing was lava pouring down the sides and villagers running for their lives.

It may have been the scariest, most gloriously decadent food product I've ever encountered (and, please, I don't want to know the caloric content or the grams of fat per mouthful). After hours of diner-hopping along Route 130 in central New Jersey, I knew exactly how George Leigh Mallory felt when he first eyed Everest -- and that's exactly why I dug into the monstrosity. Because it was there.

Jersey is the diner capital of the world (there are about 600 statewide), and Route 130, which creeps northward from about the Delaware Memorial Bridge to my home town of New Brunswick, is the diner capital of the diner capital. I've spent a fair share of my life carbo-loading in diners, though my parents deserve the credit for my surname, pronounced the same way.

So what distinguishes a diner from that greasy spoon down the street? "Three things," says Peter Genovese, a feature writer for the Newark Star-Ledger and author of "Jersey Diners." "There has to be some stainless steel somewhere, booths and swivel stools. Even the newest ones have those three things. ... You just know it when you see it."

Route 130 remains a diner stronghold, notes Mr. Genovese, because it's a "blue-collar, bumpy-asphalt sort of road. It's escaped the rampant development of the rest of New Jersey, so a lot of the diners remain."

Travelers often find themselves on 130, as it offers a decent work-around if there's traffic on the New Jersey Turnpike or Interstate 295. I spent the better part of a recent Friday trolling about 30 miles of the road -- an ugly stretch of liquor stores, Wal-Marts and warehouses -- with my friend Dan, a fellow former Jerseyan who's never met an eclair he didn't like.

Breakfast. The Harvest Diner in Cinnaminson has it all: the shiny surfaces, the booths with the mini-jukeboxes, the pages-long menu ("Burgers, Burgers and More Burgers" headlines one section). And $3.99 breakfast specials displayed in a smudgy plastic frame between the salt and pepper.

Dan detours off the bargain menu and orders an egg sandwich with pork roll (think of it as Jersey's version of scrapple, a regional favorite rarely found outside the area) and home fries. I opt for the pancake special and am rewarded with three disks the size of my head that tasted just as good cold hours later.

Have to deduct points for the prepackaged syrup and the inattentive service, especially since the place is nearly empty. But wait ... we get our own carafe of coffee to fill the typically small white mugs of my diner youth. Points reinstated.

Despite my pleas to the contrary, Dan downs everything on his plate.

Pie break! Can't diner-crawl without a dessert stop, which we decide to do shortly before noon at the Dolphin in Burlington. It's much louder than the Harvest, with booths that seem more compact; either that, or we're already getting larger. The sea theme is refreshingly understated (glass etched with nautical images, jellyfish lights, soothing aquamarine color scheme), but who cares? We're here for the baked goods.

I go for the banana cream pie, which turns out to be a perfect mound of whipped cream, mushed bananas -- and chocolate! Dan's apple pie a la mode is ice cold (tsk tsk), so he sticks to the mode and leaves the apple pie intact on his plate.

Each time a truck rumbles by on 130, the Dolphin shudders a bit. I swear I see whitecaps in my water glass.

Lunch. Mastoris in Bordentown is a Jersey landmark, which explains the buses lined up outside. Inside it's a madhouse, with people swarming a warren of rooms including a pastry shop, a bar and a dining room. We ask to be seated in the diner section, where Sue the waitress immediately places a plate of cinnamon and cheese breads before us.

We scour the most intimidating menu we've come across (stock tables have larger type) and settle on the sandwich selections. There are 82 of them. Something called a "Sloppy John" speaks to me, so we order it to split, along with the aforementioned Spud Mountain.

The sandwich has layers of fresh turkey, roast beef and corned beef soaked in Russian dressing and comes with a side of slaw. We save half of it for later and concentrate on Spud Mountain, which still looks untouched when Sue comes to haul it away.

When I ask if anyone ever finishes it, she says, "Hardly anyone. Well, maybe if six people are working on it. ..."

Dinner. It's starting to get dark, so it means time for more food. The Americana in East Windsor has more of an art-deco feel than the others, with a nice woody interior, exposed beams, tall ceilings and stone walls. There are fewer booths, with tables arranged as at a fine restaurant.

But not to worry: The menu is thicker than the last book I read, with Italian chow competing with Greek and Mexican for attention. We quickly home in on something called Mile High Meatloaf, which sounds like a good candidate to split.

It's a thing of beauty, a perfectly constructed tower of beef, mashed potatoes, gravy and "frizzled onions" resting on a slab of rye bread. A guy at the table next to us (pretty beefy himself) asks what we're eating, then watches as we divide the masterpiece.

It's the first diner we leave without a doggie bag.