My guide, Adam Brown, takes no notice, squeezing open a gate in the fence and striding out to the pier's tip. Years ago, Mr Brown used to live on an old steam tug tied up at the pier. It is still there, but now it rests on the river-bottom with only the stack and part of the superstructure visible above the water.
Much more important, however, is Mr Brown's knowledge of the underside of pier 25 and the platoons of wooden piles that hold it aloft. They are, to put it mildly, rotten and ready to collapse at any moment. I ask the obvious question - are we safe standing where we are? Yes, he replies. Then he notices my photographer wandering more closely to the edge. "But I wouldn't go where he is right now."
Compact and trim at 37, Mr Brown is a diver and a marine engineer. For years, he has inspected the watery underpinnings not just of this pier but of every pier in Manhattan and of everything else fringing the island, including bridges and the four-lane FDR Drive the length of the East Side.
It is a line of business that brings many rewards. Mr Brown is passionate about rivers, the ocean and the marine environment in general. Above water, he is also president of an advocacy group, the Working Waterfront Association, which promotes the renovation of New York's massive waterfront for marine uses. But the diving can be tough also. Mr Brown dives all year, including now when the water around the city is barely above freezing.
"I have an umbilical tube for air and a communications line to the people above me but, when I'm down there, I'm really all alone and it's black and murky. It is a bit like sitting in a closed closet with a flashlight and you only have this three-foot cone of light where you can see anything," he says.
Sometimes that cone reveals unpleasant surprises. Dead pets are quite common. Mr Brown recalls a dive he took a few years ago beneath pier 26, next door to this one, when he bumped into something soft. It turned out to be the horribly distended body of a man that for one moment wrapped an arm around one his shoulders. "He was so inflated it was if his clothes had been spray-painted on to him."
It was about 10 years ago that Mr Brown first began to notice something else going on beneath the waters around Manhattan. Tiny creatures known as marine borers, which for decades had been absent because of high levels of industrial pollution, were starting to make a comeback. They are called borers for a reason - they like to eat timber. Wooden pilings such as the ones beneath this pier are their favourite.
The borers come in two varieties. One is a crustacean, Limnoria lignorum (otherwise know as a gribble), the other a mollusc usually referred to as a shipworm. Their return to New York is an ironic side-product of the city's campaign to clean up both the East and Hudson Rivers. Only last week, authorities announced that local striped bass, banned from dinner tables for the past 23 years because of contamination, are now almost fit again for human consumption.
Now the city is faced with paying millions of dollars to repair the damage. Piers will have to be torn down and, in this case - because it is part of a newly designated West Side park - rebuilt. A large section has already broken off, its concrete surface now subsiding crazily into the choppy waters. Meanwhile, a multi-million- dollar contract will soon go out to tender for initial studies into preventing chunks of FDR Drive from falling into the East River. "For a long time, people just didn't believe us. They had forgotten that borers could exist," Mr Brown explains. "Today, they are all over the place and it's getting worse".
On more than one occasion, he has been forced to close sections of road in New York without warning because of what he has found on their undersides. "There are areas where they were driving trucks on top and driving cars on top where there was nothing underneath." Those are the moments Mr Brown confronts the worst of all the dangers of his job - that part of the city might collapse on top of him.Reuse content