The jetboat ride is a RUSH! Rain slickers are provided, but unless you seal yourself right up, you're going to get wet. In colder weather, the boat's roof is in place, but we were there in the middle of summer, on a hot day, and got soaked. (Sit on the right-hand-side of the boat for bigger splashes!)
The jetboat ride departs every 30 minutes from Niagara-on-the-Lake, Ontario, and takes its passengers upstream (towards the Falls) as far as the Whirlpool. The rapids beyond that point are too strong for a boat to go through, so they don't take you all the way to the Falls, but there are other boats that do that.