Casco Bay Tours and Tickets

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.

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).

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.

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.

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.

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.