Catanduanes (/ˌkɑːtɑːndʊˈɑːnɛs/; Tagalog pronunciation: [kɐtɐndʊˈɐnes]), officially the Province of Catanduanes (Filipino: Lalawigan ng Catanduanes), is an island province located in the Bicol Region of Luzon in the Philippines. It is the 12th-largest island in the Philippines, and lies to the east of Camarines Sur, across the Maqueda Channel. Its capital, and most populated town is Virac. Catanduanes had a population of 271,879 people as of the 2020 census.
The province comprises Catanduanes (mainland or main island), as well as the outer islands of Panay, Leyte, the Palumbanes group of islands (Porongpong, Tignob, and Calabagio), and several small islets and rocks. The province is also home to various mollusc fossil sites, notably the second-oldest ammonite site in the Philippines. These sites contain certain species of ammonites that are found nowhere else in Southeast Asia. Because of the province's importance and rich geologic history, scholars have suggested that it could be named a UNESCO Geopark Reserve.