| Mason's Island | |
| Map: | Connecticut#USA |
| Location: | Long Island Sound |
| Length Mi: | 1.2 |
| Width Mi: | .8 |
| Country: | United States |
| Country Admin Divisions Title: | State |
| Country Admin Divisions: | Connecticut |
| Country Admin Divisions Title 1: | County |
| Country Admin Divisions 1: | New London |
| Country Admin Divisions Title 2: | City |
| Country Admin Divisions 2: | Stonington |
| Population: | 399 |
| Population As Of: | 2020 |
| Area Acre: | 600 |
Mason's Island (Algonquin: Chippachaug - meaning: a separated place) is an inhabited island at the mouth of the Mystic River, in Stonington, Connecticut. The island was named after Major John Mason who was granted the island in recognition for his military services in the 1637 Pequot War in nearby Mystic.[1] This island remained in the Mason family for over 250 years, from 1651 to 1913. Since then the Allyn family have been stewards of it, and most of the island is owned by the Mason's Island Company and regulated by property deeds under the Mason's Island Property Owners Association (MIPOA). The Mason's Island Marina and the Mystic River Marina are located on the north end of the island. Mason's Island is connected to the mainland by a causeway.
The island is approximately in area overall, being in length north-south and in width east-west and is formed by solid granite bedrock. A quarry supplying rough granite for breakwaters (e.g. at Newport, Rhode Island) was located at Pine Hill on the northwestern side of the island.[2]
There is a 47acres nature preserve located in about the middle of the island. This nature preserve features a large salt marsh with surrounding woods that can be accessed by multiple trails. In the southern end of the island there is a large fresh water pond that was formerly used for harvesting ice.[3]