Casco Bay's inhabited islands stretch across 200 square miles of Maine coastline, each offering distinct landscapes and activities. This guide covers what you can do on the six year-round islands served by Casco Bay Lines, from trail networks to historical sites. Plan your visit with ferry schedules, seasonal considerations, and practical details for a day or multi-island trip.
Quick answer
Casco Bay Islands things to do include hiking coastal trails on Peaks Island, visiting the Bailey Island fishing community, exploring World War II fortifications on Great Diamond, cycling Chebeague Island's 12-mile road loop, walking Cliff Island's quiet village paths, and touring Long Island's historical district. Most activities are free or low-cost. Ferry service operates daily from Portland's Commercial Street terminal, with round-trip passenger fares at 16 USD per adult.
Peaks Island receives more than 100,000 visitors annually, making it the most accessible starting point for island exploration. The island maintains five miles of paved roads suitable for walking or rented bicycles, with the perimeter loop passing rocky beaches, forested sections, and residential neighborhoods. Battery Steele, a concrete fortification built in 1942, occupies the island's southern edge and remains open for self-guided exploration. Chebeague Island spans roughly five square miles, the largest in Casco Bay. A 12-mile road circuit connects the island's north and south ends, passing working farms, stone beaches, and the Chebeague Island Historical Society museum. The museum operates seasonally and displays artifacts from the island's shipbuilding era and summer resort period. Visitors can rent bicycles near the ferry landing or bring their own. Great Diamond Island offers two miles of walking paths through wooded terrain and along the shoreline. Fort McKinley, a decommissioned military installation, dominates the island's eastern side. The fort's stone structures and earthworks are visible from public paths, though most buildings are now private residences. Bailey Island, accessible by bridge from Orr's Island, features the Giant's Stairs, a geological formation of stacked granite ledges carved by wave action. Cliff Island and Long Island serve year-round communities with smaller visitor populations. Cliff Island has one unpaved road and a network of footpaths that lead to coves and tidal pools. Long Island maintains a historical society, a general store dating to the 1920s, and several churches open to the public. Both islands require advance planning since ferry service is less frequent than to Peaks or Chebeague. Ferry departures from Portland begin at 05:00, with the morning schedule offering the most flexibility for visiting multiple islands in one day. Each island has distinct topography and infrastructure, so activities on Casco Bay islands range from structured tours to unguided exploration of natural features.
“Battery Steele's concrete chambers and Gun emplacements remain the most intact World War II coastal defense structure in New England.”
The best time to explore the Casco Bay Islands is during the early morning arrival window of 05:00–10:00 to avoid long queues. The ferry terminal operates daily from 05:00–23:59, providing consistent access throughout the week.
Warm, 70–80°F, ideal for water activities.
Expect high demand and frequent ferry sailings for island hopping.
Mild, 60–70°F, comfortable for walking.
These months offer a balance of accessible ferry schedules and manageable crowds.
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Arriving between 05:00 and 10:00 ensures shorter wait times at the terminal.
Verdict: The best time to visit is on a weekday morning between 05:00 and 10:00 during the months of May or September.
Casco Bay serves as a gateway to several distinct islands, each offering unique opportunities for coastal exploration. Visitors can experience a variety of environments ranging from historic military sites to quiet seaside walking paths.
Known for its circular road, this island features scenic coastal views, galleries, and the Fifth Maine Regiment Museum. It provides a relaxed atmosphere suitable for walking or biking around the perimeter.
Rent a bicycle near the landing to see the entire island.
This island is characterized by its residential community and the historic Fort McKinley, which features distinct brick architecture. It serves as a quieter destination focused on architecture and peaceful shorelines.
Walk the perimeter paths to view historic fort structures.
A destination for those seeking a slower pace, this island offers expansive beaches and rural landscapes. Visitors often explore the golf course or the local historical society museum.
Visit the local museum to learn about island maritime history.
A smaller, primarily residential island that offers a sense of seclusion in the bay. It is popular for its private feel and calm water views.
View the island from the ferry deck while passing by.
The ferry terminal serving the Casco Bay Islands is located at 56 Commercial Street, Portland, ME 04101. Access to the island ferry system is centralized at this waterfront facility.
I-295 to Exit 7 (Franklin Street), follow toward the waterfront to Commercial Street
METRO BREEZE or local METRO service to Portland Transportation Center or downtown
Walk from downtown Portland or the Old Port district toward the waterfront
Casco Bay Lines ferry departures from the Portland terminal
Plan to arrive between 05:00–10:00. Early arrival avoids long lines for popular morning ferry departures.
A successful island day starts with the right prep—gear for changing weather, cash for small vendors, and flexible timing.
Everything you need to know about casco bay islands things to do
Finding the best casco bay islands things to do involves planning your ferry route from the Portland terminal to explore various coastal landscapes. Passengers often enjoy walking, cycling, and sightseeing along the historic shoreline.
The round-trip passenger fare to islands is 16 USD per adult. This fee covers your transit across the bay on the public ferry system.
For those seeking a smooth start to their casco bay islands things to do, the best arrival window is 05:00–23:59. Arriving between 05:00–10:00 is highly recommended to avoid long lines for popular morning ferry departures.
Visitors can certainly visit multiple islands by utilizing the various stops on the ferry line. This flexible approach allows you to curate your own schedule while enjoying Casco Bay excursions.
Many travelers find that a guided Portland boat tour provides excellent context for local landmarks. These narrated trips are a popular way to organize your casco bay islands things to do.
Essential items for your trip include comfortable walking shoes, water, and sun protection for your coastal adventure. Be sure to check the ferry schedule to ensure you have enough time for all your planned activities.