Penobscot Bay is home to more than one furnished island for rent. Doliver isn't one of them. It's tennis-court-size and rocky, with one tree and a sign. Stop at the Old Quarry Store, in Stonington, on Deer Isle, to pick up a kayak, a chart, and a fog forecast (207-367-8977). Doliver is a half-day's paddle south. Spend a day or two visiting some of Doliver's 60-plus granite neighbors, many managed by the Maine Island Trail Association. Permits aren't necessary; getting there early is.