It is hard to believe that all these outdoor activities are located in the midst of a wooded area of busy Rockville, Maryland! I went with my teenage daughter, and although was a bit pricy (about $100 for the two of us) , it really was a great deal of fun.
It is not a huge amount of exercise, though. (For that, the Billy Goat Trail is free and one of the area's great bargains.) But it is a great activity to do once every year or so or for a special occasion.