Great Diamond Island

Rural area · Maine

Great Diamond Island

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Best timeMay–Sep
From you
Nearest airportPWM · 6 mi
On this page

Overview

Great Diamond Island is an island located in Casco Bay in Maine and part of the city of Portland.

1 sights · 1 places to eat · 1 places to stay

Updated from Wikivoyage on 1 October 2026 · Something wrong or missing? Improve it on Wikivoyage

Best things about Great Diamond Island

Fort McKinley Museum

Displays of relics from the fort that was located on the island from Spanish-American War through the end of World War II.

Plan your trip

Best time to visit & weather

Most comfortable: May–Sep. Summer highs reach about 80°F; winter lows dip to about 16°F. Cold months (Jan, Feb, Dec) can bring snow and ice; check road conditions. Wettest: Oct and Dec. (climate data from nearby Seacoast)

Jan: 3.6 in rain3.6"Jan: high 33°F, low 16°F33°16°JanFeb: 3.6 in rain3.6"Feb: high 36°F, low 18°F36°18°FebMar: 4.8 in rain4.8"Mar: high 43°F, low 25°F43°25°MarApr: 4.6 in rain4.6"Apr: high 56°F, low 35°F56°35°AprMay: 4.0 in rain4"May: high 66°F, low 45°F66°45°MayJun: 4.6 in rain4.6"Jun: high 75°F, low 54°F75°54°JunJul: 3.9 in rain3.9"Jul: high 80°F, low 60°F80°60°JulAug: 3.7 in rain3.7"Aug: high 79°F, low 59°F79°59°AugSep: 4.1 in rain4.1"Sep: high 72°F, low 52°F72°52°SepOct: 5.0 in rain5"Oct: high 60°F, low 40°F60°40°OctNov: 4.1 in rain4.1"Nov: high 48°F, low 31°F48°31°NovDec: 4.9 in rain4.9"Dec: high 38°F, low 22°F38°22°Dec

Blue bars: average daily high and low (°F). Purple columns: average monthly rain and melted snow (inches).

Getting there

  • From you: to see whether to drive or fly, and how long it takes.
  • PWM Portland International Jetport, Portland — 6 mi away (major hub). Directions
  • AUG Augusta State Airport, Augusta — 49 mi away. Directions

There are several water taxis available near the Ferry Terminal.

Full “Get in” guide ↓

Budget & where to stay

No prices are listed for this place yet. See the Sleep guide ↓ for options.

Food for you

What to ask about, for your diet

    Diet labels come from each listing's description and cuisine; “likely” means the cuisine usually has good choices, not a promise. Check with the restaurant. Open the food finder

    Get in

    There are several water taxis available near the Ferry Terminal.

    Place Casco Bay Lines

    Ferry to all the major islands.

    📍 56 Commercial St, Portland, ME (ferry terminal)☎ +1 207 774-7871
    MapsWebsite

    Get around

    There are no cars on the island. Most people get around using golf carts or walking.

    See

    See Fort McKinley Museum

    Displays of relics from the fort that was located on the island from Spanish-American War through the end of World War II.

    Maps

    Do

    Outdoor activities include kayaking around the island.

    Buy

    Shop Diamond Cove General Store

    Offers convenience items, sandwiches, hot foods and fresh lobster.

    ☎ +1 207 766-3087
    Maps

    Eat

    Sleep

    Stay Great Diamond Rentals

    Vacation rentals available on the island.

    MapsWebsite

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    My experience

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