Katahdin
Since this is the tallest mountain in maine, it is also is the most challenging climb in Maine but the views are worth it. I have hiked all the trails that bring you to the highest peak and most of the trails have been completed more than once. I also hike the mountain in the winter via the Abol trail which ends up being over 15 miles. The winter ascents are the hardest hikes I have ever been apart of.