Coney Island is hopping today, with City beaches officially open and Nathan's Famous celebrating its 100th anniversary with a special promotion. NY1's Erin Clarke has more.

Coney Island, along with the city's other eight public beaches, officially opened Saturday.

And by midday there were plenty of umbrellas on the sand, sun bathers out and kids splashing around.

But many came for more than just fun in the sun.

A line wrapped around Stillwell Avenue and down to the famous Coney Island Boardwalk.

What could they be waiting for?

"The first hot dogs being sold at five cents since 1916."

That's right! Saturday Nathan's Famous celebrated 100 years with a special promotion — a hot dog for a nickel, just like it was when the business began on this very corner of Surf and Stillwell Avenues a century ago.

"Nathan Handwerker created not only a great hot dog, but a great American story," said Wayne Norbitz, President and COO of Nathan's Famous. "He opened a nickel hot dog stand right where we are today in Coney Island and now a hundred years later we're selling 500 billion hot dogs a year."

Hundreds came from near and far.

"We drove up from North Carolina when we heard about it and the kids wanted to come out today," said one beachgoer.

To mark the historic day with hot dogs made their way:

"Mustard,  sauerkraut, sometimes relish," said one.

"I generally just go with mustard," said another.

"I like everything, especially relish," said a third. "Relish, mustard and ketchup."

Some even sacrificed sleep like this guy who showed up at 1 a.m. He came straight from Friday's Met's game.

No doubt he's a New Yorker.

"I knew it was gonna be crowded," the weary baseball fan said.

Among the crowd, also some just here for the nostalgia of it all.

"This is a picture from the 1920s when everything was a nickel and you can see all the prices on the sign," said Brooklyn Historian Ron Schweiger. "This sign is the same when you look behind me up here is the same sign today."

And what better day for Nathan's 100th Anniversary than the first day of the beach season?

The combination of good food and good weather made for the perfect unofficial start of summer and the holiday weekend.