OceanFinds
Maine Community guide

Sea Glass Beach, Great Diamond Island

Portland, Cumberland County · 04109

Casco Bay island beach near Diamond Cove, famous for abundant colourful glass from an old military dump, open to island guests.

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About Sea Glass Beach, Great Diamond Island

This cove on Great Diamond Island in Casco Bay, also known as Pleasant Cove Beach, gets its nickname from the quantity of smooth, colourful glass on the shore. Signs on the beach explain that the glass comes from a former US military dumping ground linked to Fort McKinley. The island is reached by Casco Bay Lines ferry from Portland.

Sea glass at Sea Glass Beach, Great Diamond Island

Abundant glass in many shapes, sizes and colours. Check the low-tide line for dark 'pirate' glass and the high-tide line for lavender and sea-foam blue; old pottery also turns up.

Visiting Sea Glass Beach, Great Diamond Island

Getting there
Casco Bay Lines ferry from Portland to the Diamond Cove stop (about 30 minutes), then roughly a 10-minute walk from the Inn at Diamond Cove.
Safety
Check the tide times before you go and head out on a falling tide, so you're never cut off. Keep away from the bottom of cliffs, wear sturdy shoes on rocks, and follow the collecting rules above.
From the community

Hunters' photos of Sea Glass Beach, Great Diamond Island

From the community

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      Sources

      • newengland.com : New England Today: prolific sea glass beach near the Diamond Cove dock; check public vs private areas.
      • beachcombingmagazine.com : Beachcombing Magazine: abundant glass of many colours; only lodging guests may walk the island; take only a little.
      • smartertravel.com : SmarterTravel: 'sea glass beach' nickname; signs say the glass is from a US military dumping ground.

      Last updated 24 October 2026

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