New York City hasn't experienced a big hurricane since 1938 and if some of the current models are accurate the impact could be catastrophic.

A simulation done by the National Oceanic and Atmospheric Administration shows what a Category 2 hurricane could do to a tunnel linking Brooklyn and Manhattan. Donald Cresitello with the U.S. Army Corps of Engineers mapped out some worse-case scenarios.

"If a storm were to occur, it could be catastrophic, given the population density in the Northeast," Cresitello said.

National Hurricane Center computer models and comprehensive studies are chilling. If the worst-case scenarios come true, the impact could be devastating.

Water would be pushed into lower Manhattan, steadily rising. Seawater would pour through the Holland and Brooklyn Battery tunnels.

JFK airport would go under an astounding 20 feet of water. The famous Fulton Ferry boat landing in Brooklyn, a popular spot for young couples to take wedding pictures, could also end up under water. Wall Street could find itself in deep water - about 7 feet. The subway system could also be knocked out.

Coastal geologist Nick Coch, himself a New Yorker, says that a major hurricane could have catastrophic effects.

"Because the most dangerous thing in New York is the New Yorker," he said. "And the New Yorker thinks they've been tested by everything, but very few New Yorkers have been in the eye of a hurricane and know how uncontrollable the energy is."

For years, Coch has been sounding the alarm about how vulnerable New York City is because of its topography. He says storm surges could trigger massive flooding in low-lying areas, particularly lower Manhattan – even if the city is spared a direct hit.

'There's going to be glass all over the street, glass flying through the air," he said.

One study puts economic losses from a Category 3 hurricane at $100 billion.

"Metropolitan areas have high population density and very expensive properties," Jeanne Salvatore of the Insurance Information Institute told CNN. "So you throw a hurricane into that scenario, and the results can be really catastrophic."

There is a plan in place, if necessary, to move 2.3 million people out of coastal zones. But how many will go? Dolores Orr, head of the community board in Rockaway, says that could be a problem.

"For those that were raised here, I hear them today talking that they're not going anywhere," she said. "And that's a concern."

Steve and Debbie O'Sullivan and their three children live in Rockaway Beach in Queens, New York, a tranquil place with a wide and beautiful shoreline. They didn't worry about hurricanes, until Katrina struck the Gulf Coast in 2005.

"We never really understood, you know, the greater impact of it," Steve Sullivan said. "We never had a great fear. We used to play out in them."

The O'Sullivans, whose house sits just one block from the ocean, with the Atlantic on one side and Jamaica Bay on the other, are stocking up on hurricane supplies.

For the O'Sullivans, being prepared just makes sense; even in New York, where hurricanes are as unheard of as the Yankees not making the playoffs.

However, Coch says most New Yorkers need to remember that a Category 3 hurricane made landfall in 1938 on the eastern edge of Long Island in Southampton in 1938. The "Long Island Express" caused widespread damage, even about 70 miles to the west in New York City.

"It made Shinecock Bay a branch of the ocean," he said.

"[It's] the New Yorkers," Coch said. "Because they don't listen. You can always tell a New Yorker, but you can't tell them very much."