The Rock, and Lake Koshkonong just upstream, are dingy and opaque, not the crystal blue of Buffet's musical pictures. But the Anchor Inn has that Margaritaville feel just the same.

Big boats roared up and down the river behind Straight, some vying for spaces at the Anchor Inn docks. Personal watercraft, the generic name for those aquatic motorcycles, added their higher pitched voices to the din.

A little boy walked in the sand just a few feet from Straight, ignoring the musician. A couple of jaded mallards browsed along the shore between the piers.

Guys in tank tops or no shirts at all, and young women in shorts and swimming suit tops sat in the sun on the tavern's outdoor deck, drinking beer and eating sandwiches. A tuned, tanned foursome played volleyball on a sand court--mixed doubles.

Cars whizzed by almost overhead: Anchor Inn sits on a spit of land bounded by the Highway 59 bridge over the Rock River and the river itself.

Behind the bar, an old man directed traffic in the parking lot, which was jammed with the cars of revelers and boaters. Drinkers jammed the inside of the dark, cool bar, too, and John Kinnett, the owner, and other bartenders made drinks and set up beers fast and steady.

When he got a break, Kinnett came out and leaned against an outdoor counter to talk about the Anchor Inn.

"It's a mix," Kinnett said, referring to his clientele. "Mostly we cater to the boaters--probably 40 percent. They're out here just to have a good time, play in the sun and show off their toys."

And it isn't all young, buffed, sun-burned types, Kinnett said. Groups of 60-year-olds in pontoon boats tie up next to the kind of boats that Starsky and Hutch would drive, if those '70s TV cops had driven boats.

Sure enough, an old couple waits at a picnic table for their adult daughter to bring their lunch from inside. Their grandchild sits with them, along with a blue-eyed husky that solemnly checks out passersby.

"There may be a perception that it's more of an Illinois crowd," Kinnett said. But that is only because it is a weekend, and a holiday weekend at that.

During the week, Anchor Inn draws mainly from nearby Edgerton and Janesville and other communities nearby. Those locals comprise an important part of Kinnett's business.

"Thursday we set a record," Kinnett said. "A hundred thirty eight steaks in three hours."

Kevin McGrath, who filled his boat's gas tank at an Anchor Inn pump, can claim local and Illinois status. He lives in Hindsdale, Ill., and has a summer place on the lake.

"I've been coming up here for about 14 years," said McGrath, who has a wife and two children. "I try to come up as often as I can."

McGrath knows that the influx from Illinois irritates some Wisconsin residents.

"I think we add a lot to the economy and I pay a good amount of taxes," McGrath said, before joining the circle of offshore boat traffic.

"Right now this is good," Kinnett said, referring to the amount of beer his place is selling and the gallons of gas pumped at his pier. "Two weeks ago the river was down another foot. I could only get one boat at my piers. That's probably the number one complaint."

He bought Anchor Inn four years ago as an investment, Kinnett said.

"Little did I know how much work it would be," he said wryly, itching to get back inside and manage the outflow of food and drink.

Straight finished a Seeger tune, to sparse applause, and took a break. Recorded music blared from the speakers, punctuated with the staccato idle of a huge power boat holding in the current.

The smells of gasoline, boat exhaust and coconut oil on exposed skin mingled in the breeze. "Bring me two pina coladas," the singer sang, and Kinnett hurried off, as if to comply.