When people think of cruising they don't normally think of Niagara Falls, but on Hudson River small ship cruises, a stop is made in Buffalo, New York. From Buffalo, it is a short 30 minute ride to Niagara, New York. In Niagara New York, there is Niagara Falls State Park. From the park you can see the falls close up, stroll along the rapids or explore Goat Island which is right in the middle of the Niagara River connected by foot bridge..
If you would like to get wet, there is the Maid of the Mist. The excursion boat which takes you so close to the falls that you actually get saturated by the mist (of course they hand out rain ponchos). There also is the 'Cave of the Winds' where you can walk along a series of boardwalks and steps that wind along the base of the Bridal Veil Falls. Here too you can sense the power of the falls and get wet.
If you would like to venture to the Canadian side of Niagara Falls, you will need an official picture Id and a passport and/or Certified Birth Certificate with a raised seal. Starting December you will need a passport to cross the boarder into Canada and re-enter the US.
From the Canadian side you can some excellent pictures of the Horseshoe Falls, Bridal Veil Falls and the American Falls. The Maid of the Mist ride is available from the Canadian side as well. There also is the Journey Under the Falls, which is a series of tunnels which take you behind the falls. There also is a viewing platform as part of the tour where you can get impressive close up pictures of the falls - so close you actually get wet!
The Canadian side is very commercial with many attractions located on Clifton Hill. At Clifton Hill there are places to eat, museums, including Ripley's Believe it or Not, and more. Be prepared the Canadian side it quite pricey and the US dollar to Canadian is not very strong.
If you have already been to the Falls, I would recommend going to Old Fort Niagara, located on the New York side, right at the point where the Niagara River meets Lake Ontario. This fort, dates back to the 1700's and offers insight into how the British, French and American soldiers lived at the picturesque fortress during the times of peace and war.
Either by land or sea, if you have never been to Niagara Falls, I highly recommend going at least once.