Casco Bay

The Basics

Keep an eye out for birds, seals, and the occasional whale while you hike along the coast, sail through the harbor, or hop on the ferry to visit Casco Bay’s seven accessible islands.

Most bay tours leave from nearby Portland, Maine’s capital city, and sometimes include a city tour along with a coastal sightseeing excursion. You can also opt for a private charter vessel in order to see Casco Bay’s lighthouses and historic forts at your own pace.

Things to Know Before You Go

• Casco Bay is a must-see for nature and history lovers.

• With relatively calm water conditions and multiple islands to explore, Casco Bay is a great destination for families with kids.

• Remember to bring comfortable shoes and sun protection.

• It’s a good idea to dress in layers, as the weather can change quickly in this coastal region.

• Ferries from Portland to the islands in Casco Bay are accessible to wheelchairs and strollers.

How to Get There

Casco Bay is located just north of Portland, Maine. Ferries operate daily between Portland and the islands of Casco Bay, and private charter vessels travel through the harbor as well.

When to Get There

You can visit Casco Bay year-round, but summer is a lovely time, when the days are usually sunny and warm. Head out onto the water at dusk to see colorful sunsets over the bay.

The Casco Bay Islands

Don’t miss Peaks Island, which is home to beaches, restaurants, and an art community, while Long Island is known for its hiking trails and conservation areas. Bailey Island is also a good hiking spot, while Diamond Cove (located on Great Diamond Island) is home to Fort McKinley—a structure designed to defend Portland Harbor during the Spanish-American War.

Which island is best to visit in Casco Bay?

That depends—there’s plenty to consider. Casco Bay in Maine is home to hundreds of islands, which range from small and uninhabited to populous and popular. Some of the best to visit include Peaks Island (the closest to Portland), Great Diamond (home to Fort McKinley), and the scenic Chebeague Island.

Why is Casco Bay called Casco Bay?

There are multiple theories about the origins of Casco Bay’s name. Abenaki native people called the bay “Aucocisco,” which may have been shortened by European visitors. As an alternative theory, some believe it was named by Portuguese explorer Estêvão Gomes in 1525, thanks to its resemblance to a helmet (casco).

How many islands are in Casco Bay?

Although a popular myth suggests that there are as many islands in Casco Bay as there are days in a year, the bay contains far more. According to current estimates, there are a staggering 785 islands, islets, and exposed ledges scattered across Casco Bay.

What is the most populous island in Casco Bay?

Peaks Island—the most populous island in Casco Bay—is also the closest one to Portland. Home to around 1,000 permanent residents (alongside an additional 2,000 residents in summer's high season), the island is 17 minutes by ferry from Maine’s largest city—and it's thought of as Portland's bonus neighborhood.

Which animals are in Casco Bay?

Boasting unspoiled New England coastal scenery and habitats, Casco Bay is home to a wealth of wildlife, including harbor seals and gray seals, as well as lobster, bluefin tuna, porpoises, and dolphins. The bay is also frequented by migratory whales, including humpback, pilot, finback, and minke whales.

Which birds are in Casco Bay Maine?

Casco Bay is home to numerous aquatic bird species. Birdwatchers come from far and wide to catch glimpses of the bay’s northern gannets, Manx shearwaters, petrels, sandpipers, terns, cormorants, and more. If you want to embark on a birdwatching excursion, follow the Casco Bay Birding Trail—and keep your eyes peeled.

Ways to explore

Casco Bay is best navigated by ferry or boat tour, with multiple options and departures from Portland. The bay’s charm comes from its mosaic of islands, working waterfront, historic lighthouses, and abundant wildlife.

Visitors can experience Casco Bay on a scenic harbor cruise, the historic mailboat run, or island‑hopping ferries that allow you to disembark and explore. For thrillseekers, some tours include excursions in rigid inflatable boats. Whether you prefer a short cruise with a local expert or a full day discovering multiple islands, there are options for tours and self‑guided adventures alike.

Accessibility

Ferries in Casco Bay provide ADA accommodations, including assisted boarding and wheelchair access, upon request.

Age limits

None

What to pack

Light jacket, sunscreen, water bottle, camera

What to wear

Comfortable walking shoes, layered clothing for coastal weather

Not allowed

Littering, disturbing wildlife

Amenities

Restrooms on the ferries and in the ferry terminal, food and drink options near Portland’s waterfront

Address 

Portland, Maine, serves as the primary gateway to Casco Bay. Most tours of the bay region originate from Portland’s ferry terminal along the waterfront. There are no bridges that connect the bay’s islands, so all access is by ferry, private boat, or tour boat.

Driving

Portland is easily reached by car via I‑95 or I‑295 from Boston (about two hours away). Downtown Portland, the waterfront, and ferry terminals are readily accessible, with nearby public parking for visitors.

Public transportation

METRO is Portland’s public bus service with stops near the Casco Bay Lines Ferry Terminal on Commercial Street. Taxis and rideshares also provide convenient transit to waterfront departure points.

Best times to visit

Morning tours of the bay bring calmer seas and clearer views for sightseeing.

Best days to visit

Weekdays tend to be less crowded than weekends, especially during the summer high season.

Best months to visit

Although June to August might see the most tourists, it’s for good reason—the weather is at its best and ferries and tours operate on full schedules, making these ideal months to visit. Spring and fall offer fewer crowds in exchange for cooler temperatures.

Special events

Seasonal music cruises, sunset sails, and holiday runs take place throughout the year.