Seacoast United Mariners is an American soccer team based in Portland, Maine, United States. Founded in 2011, the team made its debut in the Northeast-Atlantic Division of the National Premier Soccer League (NPSL), the fourth tier of the United States soccer league system, in 2012. The team is operated by the Seacoast United Soccer Club, alongside division rivals, the Seacoast United Phantoms.
The Mariners began play in the Northeast-Atlantic Division of the National Premier Soccer League in 2012. Seacoast United Mariners was originally founded in 1986 as Costal Soccer Club.