From the Niagara Gazette:
Since Franciscan monk and explorer Louis Hennepin became the first European to encounter the “Falls at Niagara” in 1658 we could call him the first “tourist,” but let’s start in the early 19th century. We will begin around the time of the construction of the Erie Canal on July 4, 1817 in Rome, New York, which opened the door to travel (and commerce) across the state of New York.
Over in Niagara Falls Ont., Thomas Barnett opened an attraction named “Behind the Sheet” around 1818 and began offering tourists a tour for $1 which included a walking tour down enclosed stairs to the base of the Horseshoe Falls and along a short ledge behind the falling water. A spiral staircase was constructed in 1832 for visitors to enter the “Sheet of Falling Waters.” For an extra $1, certificates were issued to those who had completed the trip.