Nearly a third of Shelter Island's eight-thousand acres is given over to the Mashomack Preserve. Owned by the Nature Conservancy, Mashomack is a haven for piping plovers and least terns and a lot of other birds I'd never heard of before reading about them in the little visitors center. There are shaded paths through beech and oak forest that feel like Vermont, and big-sky fields that remind me of the Australian bush. Only when you follow one of the trails down to a cove and see the sailboats in the distance are you reminded that you are anywhere near civilization, let alone the Hamptons.

Shelter Island is more Mayberry than Maidstone. Even outside the preserve there is a deep sense of rural calm. Everything is green. The lawns are every bit as luxurious as elsewhere in the Hamptons, although the houses aren't as big or ornate. Driving past osprey nests and over an isthmus, you come to Big Ram Island, where the buttoned-down, seersucker-and-bucks-style Ram's Head Inn is housed in a fine old colonial structure.

The Heights Pharmacy has an old-time soda fountain and sandwich counter in the back. An American flag hangs in the window, next to a list of movies playing in town and flyers for yoga classes and a boat someone is selling. The only incongruous note is a welcome one: Down Shore Road, on the way to Jennings Point, is a little piece of the Riviera called Sunset Beach—a twenty-room waterfront inn owned by André Balazs, of the Chateau Marmont in Hollywood and The Mercer in SoHo. Balazs is a master at creating just the right mood, and Sunset Beach somehow fits in even as it stands out. The bar is fun. The rooms are simple and nearly all white. The staff seem like French au pairs with hangovers. In a good way.

Heading back toward East Hampton, we take a detour through the hamlet of The Springs and find ourselves in yet another world apart. The house on Fireplace Road where Jackson Pollock and Lee Krasner once lived and painted is a museum now. We stop in at the Springs General Store, an old brown-bag grocery with Adirondack chairs on the front porch and a little yard with picnic tables. I order a Jackson Pollock burger and splatter it with ketchup in an abstract homage. We follow the thin ribbon of Old Fireplace Road to where it dead-ends at a lovely empty cove and beach. The water's surface shines like glass. A kayak floats by. Behind us is Accabonac Bay. It was from Accabonac that the old islanders took their nickname: Bonackers. At first the name was an insult, according to East Hampton, A History & Guide, akin to "lazy clam digger. Subsequently, it has become a chauvinistic badge."

The name Fireplace crops up a lot around here because this is the shore where fires were once made to send signals to the landowners across the bay at Gardiners Island. Gardiners was settled in 1639 by one Lion Gardiner, the first Englishman to reside in New York State. It is a living, unbroken link to the history of New York and America itself. Captain Kidd buried treasure there. British troops stored provisions there during the Revolution. And in three and a half centuries, it has been passed down from one Gardiner to another. At more than three thousand acres, it is the largest private island in America. Real estate agents dream about it. Environmentalists worry about its development. And until recently the Gardiner family fought over it. Robert David Lion Gardiner, the sixteenth lord of the manor of Gardiners Island, died two years ago, leaving the title of the land to a niece he'd feuded with. Gardiner was once asked how the family managed to keep their grip on the island for so long. "We've covered all our bets," he answered. "We were on both sides of the Revolution and both sides of the Civil War. The Gardiner family always came out on top."