Six of Casco Bay’s islands have year-round populations and are served by scheduled ferries from downtown Portland. Except for Long Island, the islands are part of the city of Portland. The ferries provide an inexpensive way to view the bustling harbor and get a taste of island life. Trips range from a 20-minute (one-way) excursion to Peaks Island (the closest thing to an island suburb, with 1,000 or so year-round residents) to the 5 1/2-hour narrated cruise (with a long lunch stopover) to Bailey Island (connected by bridge to the mainland south of Brunswick) and back. All of the islands are well suited for walking; Peaks Island has a rocky back shore that’s easily accessible via the island’s paved perimeter road (bring a picnic lunch). There’s also a bike rental outfit a few blocks from the island’s ferry dock. Long Island has a good hidden beach. Cliff Island is the most remote of the six-pack, with a sedate turn-of-the-20th-century character.