THE New York subway system is horribly complicated, like a ball of string that has unravelled at random over and under America's largest city. Coney Island is the biggest tangle. B-trains, D-trains, N-trains - and trains that seem to have nowhere else to go - rattle along to the seashore.

A couple of hundred yards from the Atlantic Ocean, they congregate in a railway version of alphabet soup. The station called Coney Island/Stillwell Avenue is a three- storey steel lattice of tracks and points and platforms.

Reaching New York's seaside underworld is part of the fun. The D-train from Manhattan erupts from Chinatown to climb steeply, levelling out 200ft above the East River. The locals are as oblivious to the arrogance of Manhattan's cityscape behind as they are to the daunting view ahead of burnt-out factories and boarded-up buildings. The D-train descends, pierces Brooklyn round about its heart, and slithers underground for half a dozen more stations. When it surfaces again, though still in the borough of Brooklyn, it is a different world: the threatening tenements have been replaced by neat suburban bungalows. Americans do not just live in suburbs, they also celebrate them. This is, after all, the nation that invented the shopping mall to serve suburbia, and one of General Motors' biggest-selling vehicles is a van called the Suburban.

Stay on the train through the suburbs and you end up at Coney Island - not an island at all, but a spit that dangles from Brooklyn into the Atlantic. Being a suburb of a suburb places Coney Island way down the municipal hierarchy, but this two-mile stretch of seafront is the most fascinating, entertaining and strangely beautiful place in New York City.

The island's former magnificence is written in the street names - Surf Avenue, Neptune Boulevard - and the awesome, gaunt geometry of the silently rusting rollercoaster and Ferris wheel. The whole resort breathes decline and decay. Before the war, a million people would congregate at Coney Island on summer Sundays, but New Yorkers became more mobile and sought sun and sea beyond the subway. While Florida and Hawaii have boomed, most of Surf Avenue's banks and businesses are only faded facades. At No 1220, for example, bilious green cornices announce a once- imposing family business called Herman Popper & Brother.

Though outer-city decline has set in with a vengeance, the planks of the boardwalk, bleached by countless storms, have retained their spring. The sturdy wooden promenade acts as a frontier between the resort's attractions (to use the term loosely) and the beach. At 30 yards wide, the boardwalk is far too broad for the number who take the air on it these days - but thrilling for its scale and emptiness, none the less.

Past the New York Aquarium (dial 265-FISH for information), you cross the invisible line that divides Coney Island from Brighton Beach. This suburb, which stole its name from its Sussex sister, fails to be sophisticated, just as Coney Island fails to be raucous.

Here, beneath the flight path to Kennedy airport, a sign reads: 'No dogs, no fires, no tents' - in Russian. This is not because budget travellers from Moscow and Minsk are bringing their animals and camping on the beach, but because immigration from the former Soviet Union is concentrated on Brighton Beach. Many of the arrivals are from the Ukrainian resort of Odessa, and the beach, a golden strand stretching for miles, like the one in their home town, must be one reason why they chose this part of New York. Even on a grey autumn afternoon, with the sand sliding into steely Atlantic waters, the attraction is clear.

No one goes to New York to swim, but perhaps they should. As it is, the only people on the beach are a handful of joggers and a few Russians illicitly exercising their dogs (there is no evidence of illegal camping). Everyone else is a block away from the seafront, bustling along Brighton Beach Avenue. This is a jumble of market stalls, apartment blocks, liquor stores and cafes. The dominant alphabet is Cyrillic, and it feels like a lively Moscow street market, were there such a thing.

Another distinction from the former Soviet Union is the prevalence of places to eat and drink. Kholodnoye Pivo sounds as if it might be a fur-trappers' settlement in Siberia, but it means 'cold beer' - easier to find in Brooklyn than back in the old USSR. The best blinis (soft pancakes wrapped around mushrooms and cream) this side of the Black Sea are served in the cafes of Brighton Beach, in the untidy side streets beneath the elevated rail tracks.

Along the shore in Coney Island, the native food is Nathan's Famous Hot-dogs. In 1916, Nathan Handwerker began dispensing livid, ruddy sticks of processed beef. These can be properly appreciated only when eaten with fries and onion rings, all doused in tomato ketchup. Nathan's illustrious hot-dog joints crop up all over New York City, but the original, and the greatest, is on the corner of Stillwell and Surf Avenues. For dinner, you could devour an all- day breakfast at the Nebraska Diner, on the corner of Cropsey Avenue and Shore Parkway. This definitive American diner serves an industrial-sized platter of bacon, eggs and pancakes, drowned in syrup and accompanied by endless cups of steaming coffee.

As the daylight dwindles, treat yourself to the scenic ride back to the city. Take bus B6 to the A-line (one of the few lines that does not seem to terminate at Coney Island) and join a Manhattan-bound train. A tidy fringe of trackside trees props up a blossoming sunset, while the horizon is interrupted by a hazy silhouette of the city's tallest skyscrapers. If fortune is with you, your train will subside beneath the surface at Grant Avenue at the same moment as the sun disappears behind the Empire State Building. You are heading for the core of the Big Apple, while back at the decaying edge of New York City, Coney Island is getting on with being the tangle at the end of the subway.

Getting there: Plenty of cut- price fares are available between the UK and New York's Kennedy airport, the most convenient gateway for Coney Island. Quest Worldwide (081-547 3322) is selling Heathrow-New York flights on Virgin Atlantic for pounds 170 (plus pounds 32 in taxes for departures after 1 November), but seats at this price are strictly limited. An alternative is an unrestricted London-New York ticket on Air India for pounds 199 (plus pounds 26 in tax) through Welcome Travel (071-439 3627).

Accommodation: it is difficult to find anywhere to stay in the area. Simon Calder paid dollars 80 ( pounds 55) for a night at the Harbor Motor Inn, a mile around the bay from Coney Island at 1730 Shore Parkway (0101 718 964 9200). This is not an especially relaxing place; it also rents rooms by the hour (dollars 11 an hour weekdays, dollars 12.50 weekends and holidays).

Further information: The Cadogan City Guide to New York by Vanessa Letts ( pounds 10.99) has a good section on Coney Island.

Visit USA Information Service is contactable on a premium-rate phone line, 0891 616000, 10am to 4pm. Inquiries by post to: PO Box 1EN, London W1A 1EN.

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