We returned to the boat and were soon skidding across Casco Bay. The captain phoned ahead to the single store on Cliff Island and ordered us roast beef grinders with dill pickles and mustard, and the sandwiches were waiting for us when we docked a few minutes later. Cliff, with a year-round population of about fifty, is the remotest of the islands with regular ferry service, and its children attend a one-room schoolhouse until sixth grade, at which point they make the hour-long commute into Portland for middle and high school.

Captain Gene and I returned to the open water, lunch in hand, and headed toward Jewell Island, another state park, to eat it. En route he buzzed past a series of ever more remote islets—starting with Bates, home in the nineteenth century to the mysterious Jane Bates, a self-sufficient woman who dressed as a man and survived on fishing and clamming. One day her body washed up on the shores of Richmond Island, four miles southwest of Bates, wearing a brightly colored silk kimono. No one knows how this came to pass, but one fact seems irrefutable: Jane Bates did not own a kimono. According to Captain Gene, the case is still listed as open by the Portland police.

We cruised about a mile north to Eagle Island and saw an impressive-looking mansion high on a bluff. This is the former home of Admiral Peary, credited with discovering the North Pole. The first floor of the house had been designed to feel like the pilothouse of an ocean vessel. "He loved the sea," said Captain Gene with obvious admiration, and I thought: He's not the only one.

Across a short channel from Eagle Island is Upper Flag Island. "The admiral kept his sled dogs here," said the captain. "People used to hear him standing on the deck of his house, yelling at his dogs."

A huge obelisk stands on a small island a few miles away—Little Mark, on which a man, locals say, was marooned for a month in the nineteenth century. After his rescue, the man went out into the world and made his fortune, or so the legend goes, and in 1827 built and endowed the obelisk, a monument to lost mariners, decreeing that a room within its base be kept stocked with food and water to be used by any future mariner who might find himself stranded here. The government did just that until the early 1920s, according to Captain Gene, when the money finally ran out.

We made landfall on Jewell and walked up a bluff to a good picnic spot, where Captain Gene and I enjoyed our roast beef and pickle sandwiches. "What's amazing," he said, "is that nobody knows about these places." He gestured at the beautiful horizon—the sea, the lobster boats, the hundreds of islands. "It's like the islands of Casco Bay are this great secret. And they shouldn't be secret. People should enjoy them."

He took a big bite out of his sandwich. "My grandfather used to take me here when I was a boy. They say Captain Kidd's treasure is buried on Jewell. I have a friend who swears he's found gold doubloons here."