Halfway between Portland and Bar Harbor sits Knox County, a stretch of Maine's Mid-coast with around 40,000 residents, a working harbour scene and some of the best seafood in New England. Niche.com ranks it the fourth-best county in Maine for retirement, citing home prices, healthcare and outdoor options — and CrimeGrade gives it an A- for safety, putting it in the 80th percentile nationwide.

Rockland is the county's anchor and calls itself the "Arts Capital of Maine". In summer, galleries open their doors on the first Friday of each month for the First Friday Art Walk, and the Farnsworth Art Museum holds 16,000 works of American art, many by Maine artists. Maritime history runs deep here too: the Sail Power and Steam Museum covers shipbuilding, steam engines and wrecks, while the Maine Lighthouse Museum displays lighthouse bells, lights and flags. For fresh air, the five-mile Rockland Harbor Trail loops the harbour and downtown with constant ocean views.

Then there's the food. Claws, a seasonal lobster shack on Rockland Harbour, serves lobster rolls, chowders, fried clams and lobster mac and cheese with a side of water views. Hill's Seafood Co offers indoor and outdoor seating plus a full bar, with scallops, lobster stew and fish and chips alongside burgers and steak tips for landlubbers. Come summer, the five-day Maine Lobster Festival takes over with parades, chowder, a children's programme, the Fun Run and the wonderfully odd International Great Crate Race — contestants sprint across a line of floating lobster crates in the harbour.

Just up the road, Rockport — self-styled "Town in the Middle" — suits anyone wanting a smaller-village feel, with sailing, hiking, birdwatching and trails through the Beech Hill Preserve.

Practically speaking, a single person can live in Rockland on roughly $3,000 a month, below the US average. Healthcare is covered by Pen Bay Hospital locally, with Maine Medical Center in Portland about an hour and 40 minutes away. The trade-offs are real: winters are cold and snowy, so a car is near-essential outside Rockland's walkable core. Newcomers can plug in quickly at the Rockland Community & Resource Center, which runs mahjong games, art sessions and walking groups.

Even if retirement isn't on your radar, Knox County makes a strong add-on to a Maine trip — an easy stop on the drive between Portland and Acadia, with good museums, a genuinely scenic harbour walk and lobster rolls you'll think about for months.