Salty water from New York Harbor submerged parts of a promenade at the base of the island. A foot of water rushed over the wall of a marina in front of the New York Mercantile Exchange, where gold and oil are traded.

"You could see newspaper stands floating down the street," said Scott Baxter, a hotel doorman in the SoHo neighborhood.

As the center of the storm passed over Central Park at midmorning, floodwater reached the wheel wells of some stranded cars in Manhattan, and more streamed into the streets of Queens.

Still, the storm was far from the worst fears. The Sept. 11 museum, a centerpiece of the rebuilding of the World Trade Center site, said on Twitter that none of its memorial trees were lost.

Irene weakened to winds of 65 mph, below the 74 mph dividing line between a hurricane and tropical storm. The system was still massive and powerful, forming a figure six that covered the Northeast. It was moving twice as fast as the day before.

As a hurricane, Irene had already killed 11 people and left 4 million homes and businesses without power. It unloaded more than a foot of water on North Carolina and spun off tornadoes in Virginia, Maryland and Delaware.

Even after the storm passes in the Northeast, the danger will persist. Rivers could crest after the skies the clear, and the ground in most of the region is saturated from a summer of persistent rain.