I can think of two breweries on the same island as Bar Harbor:
1) Atlantic Brewing: Outside of town. Has a decent tour & tasting with a barbeque and sandwich shop outside with good beer on tap.
2) Bar Harbor Brewing: A tiny microbrewery located in the down town area of Bar Harbor. Brewing there is on the same general scale as most homebrewers. (Um... just googled, and noticed BH Brewing got bought out by Atlantic...hope they're still there!)
If you go through Freeport, ME be sure to stop in to Grirtty's for a sandwich and a delicious pint. They are the place with a grain silo. Some people also go to LL Beans in Freeport, but they have no beer.
In North Conway, look for Moat Brewpub. I've been told I should have memories of that place...