Pororoca
The pororoca is 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 is 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, surfing the Pororoca is especially dangerous, as the water contains a significant amount of debris from the shores of the river (often entire trees), in addition to dangerous fauna. In 2003 the Brazilian Picuruta Salazar won the event with a record ride of 12.5 kilometers during 37 minutes.