Already 27% of New York City's 520 miles of coastline are parks or natural areas managed by the Parks Department. These parks are already a key line of defense in a flood, absorbing water before it reaches homes or businesses.

The city has been shoring up defenses at these parks -- building lifeguard stations and bathrooms on stilts, as seen here on Staten Island, and adding sand or stone barriers, wetlands, and vegetation that can withstand saltwater. It also added over 100 acres of new parkland in 2013.

"It's not just about rebuilding after Hurricane Sandy," said Robert Ivy, CEO of the American Institute of Architects. "It's about showing us all how to work with nature, not against it."