The river that Henry Hudson stumbled on 400 years ago beckons New Yorkers (and New York visitors) at this time of year to board a boat in New York harbor and go north as far as possible. The lure is the changing foliage but the rewards of the trip include traveling along the New Jersey Palisades, created around 200 million years ago, when molten magma forced itself from deep within the Earth through softer layers of sandstone, which later eroded, exposing the steep cliffs.
Then there are the river towns, the tugboats, barges and freighters, the bridges, the three 19th century lighthouses between New York City and Bear Mountain (including the famous Little Red Lighthouse beneath the massive George Washington Bridge), glimpses of estates with vast, manicured lawns, freight trains and passenger trains on both sides of the river, and on some trips, a peek at the United States Military Academy at West Point.
Frequently, Hudson River fall foliage expeditions will pass a very special boat -- the 85-foot-long replica of the "Half Moon" on which Hudson and his crew of 20 crossed the Atlantic Ocean and made their way up the river as far as what is now Albany before they realized that they had not found a route to Asia, and turned back.
Hudson River fall foliage tours usually start in early October and end by mid-November. One, offered by the Circle Line, is all day with a three-hour layover at Bear Mountain State Park. Others such as Circle Line Downtown's Zephyr and Classic Harbor Line's M/V Manhattan are three to five hours long and include a sumptuous spread of food, beverages and cozy lounges from which to watch the passing scene when it gets too cold on deck.
I've tried several of these excursions and recommend them all.