I haven't done a lot of the "mountain" hikes in the Camden Hills and I haven't done every single cache in these areas (there's quite a few in these areas), but I can offer a few suggestions of some of my favorites. Incidentally, you can of course research these and other caches in the area by typing in the zip code of 04915 (Belfast).
Patty's Mt. Battie (GCC0E) . . . a must-do cache as a visit to Camden is not complete until you either hike or drive to the top to see the panoramic view of the Camden Harbor. Also a nicely hid cache.
Merry Spring (GCJD3Q) . . . find the cache and then take a minute to stroll through the grounds and see the various gardens at this jewel of a spot -- or find the cache after touring the grounds
American Chestnut (GC4AEB) . . . a nice walk through the woods rewards the geocacher with a great view of the ocean . . . and a nice place to rest and contemplate the view to boot
Picnic By the Bay (GCG64Y) . . . a great park with a pool, playground equipment, tennis courts, BB court, etc. . . . and many memories for me as my parents took me here often as a child growing up. Nice view of Penobscot Bay
Shirttail (GCQVVW) . . . small park on a nice little stretch of the river. Picturesque place to relax and unwind
Some other great caches (my opinion of course . . . which does not necessarily reflect the views of geocachingmaine.org or those of its other members) in the nearby area.
Moose Point (GC420A) . . . great little walking trail alongside the ocean
Sear's Island (GC4EF4) and Up the Hill (GCQ47T) . . . when I visited these caches it was a foggy morning and the place had a real mystique about it.
Fort Point deLight (GCZ414) . . . a wicked good hide, nice view of the ocean and I have to admit I love lighthouses so this is one of my all-time favorites
Gravity Outlaw (GC9488) . . . some folks don't care much for virtuals, but this is a great one. You have got to see this rock to believe it . . . and if you look at it just right you can see the outline of a head with the eye socket, nose and even a hint of a smile
Sandy Pointer (GCGVC6) . . . another great view of the ocean incorporated with some history of the area and a good hide . . . even though I had to go twice to find it
I hope this helps . . . hopefully others will chime in with some of their favorite caches in the area.
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