CHAVES, Brazil (AP) -- Surfers from all over Brazil gathered this week at the Amazon River's mouth to ride some of the world's longest-lasting waves, when the incoming tide roars upriver in a broad band that can keep surfboards afloat for miles.
"You have to throw yourself in that vibe and integrate yourself with nature. Never try to conquer it, because that's impossible," Noélio Sobrinho, president of Brazilian Pororoca Surfing Association, said in an interview with the Associated Press.
The annual festival to ride these tidal bore waves, known locally as the "Pororoca," rotates through towns where the river meets the Atlantic Ocean and this year took place for five days through Wednesday in Brazil's Para state town of Chaves.
The waves happen twice a day when the ocean waters flow into the river, rather than the other way around. But it is especially powerful -- and surfable -- during days surrounding full and new moons, when the ocean's tide is at its highest, creating a wide and long-lasting wave that surfers can ride for up to 40 minutes.
"It's something of a different dimension," said first timer Carlos Carneiro Jr., who traveled to Chaves from the Brazilian city of Fortaleza, some 930 miles away. "You have to feel it. Surfers have to come and see what it is."
The phrase Pororoca is believed to derive from a indigenous word either for "big roar" or "destructor." The phenomenon has done its share of destruction in remote riverside communities in the states of Para, Amapa and Maranhao, but also provides them with revenue from sports tourism.
In Chaves, locals have named the area where surfers go the Dangerous Canal, an area more than 5 miles wide. Surfing there is especially perilous because the forceful waves carry abundant debris. Some surfers describe it like a tsunami.
It is also a risky expedition for boat and jet ski drivers who ferry surfers and who must avoid getting stuck in sandbanks or caught by the oncoming wave.
Sobrinho, of the Brazilian Pororoca Surfing Association, has surfed more than 200 Pororocas over the decades. His passion started when his father told him he had to ride a Pororoca to prove he's a good surfer.
"Pororoca has always been synonymous with tragedy and destruction," Sobrinho said. "After we started surfing the wave ... Pororoca went from villain to artist. Today it is one of the main sources of tourism here in Chaves."