The pororoca's a tidal bore, with waves up to 4 meters high that travel as much as 13 kilometers inland upstream on the Amazon River. Its name comes from the indigenous Tupi language, where it translates into "great destructive noise". It occurs at the mouth of the river where river water meets the Atlantic Ocean. The phenomenon's best seen in February and March. The wave has become popular with surfers. Since 1999, an annual championship has been held in São Domingos do Capim. However, su… (More on Pororoca)