The island barangays are composed of 17 barangays, with a population of 28,996. Here are some island baranggays found in carles and how they got their names:
Barangay Binuluangan was formerly named "Baliw". It was once a down stream portion of the mainland but because of the alluvialaction of the water of two streams, it got separated from the mainland, thus the term "Buluang" or breach. The sitio as it separated became known as "Binuluangan"
Sicogon is the name given to the island because of the abundance of cogon grass.It could not be recalled but the island was inhabited before the establishment of the municipality of Estancia. The commune was founded by Spaniard, Don Candido Sanchez with the early family settlers. Known barrio lieutenants were: Oro N., MarianoVillaguilermo, Cayetano N.or Tanoy, Francisco Lengonor, Tomas Alicante, Ancelmo Lopez Dizon, Inocencio Danao, Placido Placido Tuner, Daoroteo Igancio, Victor Acodician, Semion Arangot, Primitivo Arceo, Narciso Colongon, Arispulo Danao, Isidro Serafino, Gabriel de la Cruz, Pedro Mahinay, Dioniseo Moreno, Evangelista N., Martin Danao, Roman Lutay-lutay and Patricio N.
The name Calagna-an was given to the island from the Visayan word or name Dagna or Lagna because of the various water springs that are located in different parts of the island, thus the name Clagna-an.
The primitive name of Gigantes Islands was Sabuluag or Salauag derived from a tree specie endemic in the area. It was changed to isla de Gigante because the first settlers found a mortuary box made of rock and measure 8 feet in length containing colossal remains of human being. In the Danao-danao cave at Gigantes Sur, the settlers also found mortuary boxes of this kind. This prompted them to believe that the place was the cemetery of the colossal person who inhabited the island. Compose of two islands, Gigante Sur and Gigante Norte.