Jøa is an island in Namsos Municipality in Trøndelag county, Norway. The 55.3-square-kilometre (21.4 sq mi) island lies on the south side of the Foldafjord, between the mainland and the islands of Otterøya and Elvalandet. The island is partially forested, with the southern part being flat and marshy, and the northern part being more mountainous. The 297-metre (974 ft) tall Moldvikfjellet is the highest point on the island.