Approximate travel time from Portland: 20-25 minutes one-way (trip times vary based upon cargo volume)
Great Diamond Island is an island in Casco Bay, Maine. It is part of the city of Portland, Maine.
The island is not easily accessible by motor vehicle and has a limited network of roads. The primary modes of transportation are golf carts and bicycles. This fact has become a selling point for the island, marketing the area as “car free” and “kid friendly.”