Of course the biggest highlight of the area is Acadia National Park, the only National Park in the Northeastern United States. Beautiful coastline, beaches, lakes, and hiking trails. More information about the park: https://www.nps.gov/acad/index.htm There is a free shuttle that can take you all over the island: https://www.exploreacadia.com/ Make sure to buy a park pass and display it in your car (the National Park Service needs this more than ever): https://www.nps.gov/acad/planyourvisit/fees.htm#spci_1001F352-0A81-2B9E-C64E9C7DA208C954
Maine is known for lobster - and there are a number of restaurants where you can get great local seafood. We enjoyed Geddy's in Bar Harbor.
Several ferry services and water taxis are available for visiting these quaint islands. Museums, art galleries, antique shops, and lobster rolls. https://www.islandinstitute.org/community-profiles/cranberry-isles/ Ferry information: https://downeastwindjammer.com/ferries/cranberry-cove/
Renting kayaks or bicycles is a great way of exploring the island on your own terms. Paddle along the scenic rocky coastline or on peaceful lakes throughout Mount Desert Island. https://acadiafun.com/kayaks/ https://www.scottyskayakrentals.com/