Prainha is a municipality in the state of Pará in Brazil. The population is 29,846 in an area of 14,787 km². The elevation is 70 m. It is located o…Prainha is a municipality in the state of Pará in Brazil. The population is 29,846 in an area of 14,787 km². The elevation is 70 m. It is located on the Amazon River.