Please see the New York City page for details on how to get to New York City.
By Rail
There are three railway stations with access to points outside of New York City. The largest, Pennsylvania Station in Midtown, is served by Amtrak with connections all over the country; by the Long Island Rail Road which serves Long Island; and New Jersey Transit which serves New Jersey. Grand Central Station, an art deco delight, is the home of Metro-North Railroad which connects the city to points in southern New York State and southern Connecticut. Many trains from Grand Central Station also stop at Harlem/125th street, a useful stop for travelers headed for Harlem or other points in Upper Manhattan.
A subway system, PATH, connects some points in downtown and midtown Manhattan with Hoboken, Jersey City, and Newark.
By ship
Passengers from Staten Island usually take the free Staten Island Ferry to get to the Battery at the lower tip of Manhattan. The Battery also houses ferries to Liberty and Ellis Islands and Governors Island. Other ferries transport passengers to and from Brooklyn and parts of New Jersey.
By plane
While there is no airport in Manhattan see New York City for details on airports serving the area, there are helicopter and seaplane services into the city. At least two companies provide helicopter services between Manhattan and area airports (http://www.heliny.com), (http://www.flyush.com) from helipads on W34th street, E34th Street, and Wall Street. Seaplane services (http://www.shorelineaviat...) are available to East Hampton from E23rd street during the summer months. Neither are for the faint of pocket - the helicopter service costs $125+ while the seaplane service costs $425 per person. Scheduled Helicopter services are also available to the airport in Bridgeport, CT from Manhattan (http://www.flyush.com).
By road
Manhattan being an island, access whether by car, taxi, bus or by foot has generally to be made by means of either a bridge or a tunnel. A pedestrian can walk into Manhattan over the Brooklyn, Manhattan, or Williamsburg Bridges from Brooklyn, the Queensboro or RFK formerly Triboro Bridges from Queens, all the numerous small street bridges from the Bronx, and the George Washington Bridge from New Jersey. Probably the most famous of these is the Brooklyn Bridge. If you're coming from LaGuardia Airport LGA by cab, consider asking the driver to take the Queensboro or Williamsburg Bridges into Manhattan if you're going to Midtown or Downtown, respectively, and save yourself the RFK Bridge or Queens-Midtown Tunnel toll.