Northeast Harbor
"In general..."
The harbor is beautiful especially during fog. But on other days it is still a much quieter place than Bar Harbor or Southwest Harbor. There is not many options for dining or breakfast, but it has several very nice stores with exceptional quality clothes, jewelry, art objects and dining sets. I could not resist to shop twice there.
There are boat Nature tours leaving from this town - 10am and 1pm. Other tours are available also. Mail boat takes 30 min to get to Little Cranberry Island.
Pine Tree Market on the main street has organic vegetables and sandwiches - less expensive than having lunch in any cafe or restaurant.
On weekends there is always something going on, so check their schedule.
Otherwise, it is a perfect location to have a peaceful stay and have a short drive either to Bar Harbor or Southwest Harbor.

