What is a Barrier Island?

A barrier island is a narrow, elongated island that forms parallel to the mainland coast, typically separated from it by a lagoon or marsh. Barrier islands are formed by the deposition of sand and sediment by waves and currents, and they are often associated with sandy beaches and dunes. They are common along the Atlantic and Gulf Coasts of the United States, as well as in other parts of the world.

Barrier islands serve several important functions, including:

  • Protecting the mainland from storm surges and erosion
  • Providing habitat for a variety of plants and animals
  • Supporting tourism and recreation


Barrier islands are dynamic landforms that are constantly changing shape and size. They are vulnerable to erosion from waves and storms, and they can also be overtopped or destroyed by hurricanes and other natural disasters. As a result, it is important to manage barrier islands carefully to ensure their long-term sustainability.

barrier island

Anna Maria Barrier Island

gasparilla barrier island

Barrier Islands Run parallel to the mainland and as a result protect the mainland during heavy storms.

Barrier Islands are separated from the mainland by a Lagoon or a Sound

barrier island