What legal aspects should you look at when implementing a zip line in a national park as an innovation? What permits, licences or requirements are needed?

Well first you have to get a concession license from the Park Service. That will mean presenting a business plan with environmental impact study. That's assuming there is even any interest in doing it. I would check that out first.

Thanks for the response.. its actually for a law paper for an assignment.. just want to make sure that I cover the entire legal aspect to implement a zip line..

You should have specified that. Be have rules about homework questions. This assignment was given to you to show you know how to do the research, not get someone to do the work for you.