In Maine, a landowner is immune from liability if someone is injured while on the land for recreation. The only exception is if the injured person paid the landowner to be on the land, like a private campground. Folks have pressed the envelope some (for example, sued a paper company for a car accident caused by a bad road, where the injured person leased a camp from the paper company and used the road to get to the camp) and the court told the injured person to get lost. Even in the absence of statutory immunity, it would be hard to make a case against a cliff owner. I mean, assumption of the risk still means something.
Don't know about N.H.