Ibo is one of the Quirimbas Islands in the Indian Ocean off northern Mozambique. It is part of Cabo Delgado Province. It grew as an Arab trading port with the Portuguese. The island was fortified in 1609 by the Portuguese. In the late eighteenth century, Portuguese colonialists built the Fort of São João, which still survives, and the town, as a slave port, became the second most important in the region after Mozambique Island. The island is now a far quieter place, known for its silversmiths. Ibo forms part of the Quirimbas National Park and is linked by dhows to the mainland at Tandanhangue.