Marinduque, island, Philippines, in the Sibuyan Sea, south of Luzon and east of Mindoro. A substantial part of the hilly, oval-shaped island is devoted to agriculture (coconuts, rice). There are also cattle ranches and rich fishing grounds, and iron ore and copper mining are important. Boac, on the northwestern coast of the island, is the principal city. Other coastal settlements include Santa Cruz, Buenavista, Gasan, and Torrijos. The inhabitants are mostly Tagalogs. The annual Moriones Festival features street pageants performed through the Holy Week of Easter. Pop. (2000) 217,392; (2010) 227,828.