Clifton has an interesting mix of sport and trad climbing on mostly low angle rock. Acadia is 1.5 hrs away and has very nice trad climbing. Shagg is a nice place to go if its not crowded and you pull 5.12+ sport.
By M Sprague Administrator From New England Jan 21, 2014
It doesn't answer your question of what is closest, but Shell Pond (near the western border) should be put on your list of great Maine crags for sport climbing. Unfortunately, information about it is very thin here on MP, which is surprising to me considering the quality and number of routes. Jerry Handren's new North Conway guide is pretty good for western ME, including Shell, though there has been active development since it came out.