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Natural phenomenon - Every year, a rare phenomenon occurs deep in the Amazon rain forest of Brazil.

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Tidal bore - The right alignment of the sun and moon reverses the flow of the tide, meaning that the Atlantic Ocean's waters will move upstream, forming a tidal bore.

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Long and devastating - The tidal bore can travel as far as 800 km (497 miles) inland and devastates everything in its path.

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"Pororoca" -

 In Brazil's Amazon rain forest, the famous phenomenon is locally known as "Pororoca."

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Ancient - The name originates from the local indigenous language.

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Meaning - There are different views on what it means exactly, but some of the most common interpretations are that it means "great roar," "destroyer," or "great blast."

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Thunderous - This is because Pororoca can be heard way before it hits the area, with some saying as much as 30 minutes to an hour before!

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Fast and loud - It travels at speeds of 16 to 24 km (10 to 15 miles) per hour. It's like a roar that gets louder until it finally arrives.

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Meaning -

Another interpretation of the word comes from separating it into two words: "poroc" (which essentially means "to take out") and "oca" ( which means "house").

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Demolishing - This also makes sense, as the Pororoca is such a powerful phenomenon, it destroys everything in its path.

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Mearim River - The Mearim River, in particular, is a hot spot for experiencing one of the most powerful tidal bores in the world.

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Extreme surfing - Every year, surfers (like Flavio Marao (R) and Sergio Roberto) flock to the area to surf the long and dangerous Pororoca.

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Dangers - Due to its devastating force, the waves are usually full of debris, including whole tree trunks!

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Dangers - But surfers have more to worry about than just the flora, as they also have to worry about the fauna.

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Dangers - Piranhas, crocodiles, snakes, and other animals can be found in the river waters.

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Record - Brazilian surfer Picuruta Salazar holds the record of the longest wave surfed for the longest time. He rode a 12.5-km-long (7.4 mile) wave for 37 minutes.

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Riding the Pororoca - Brazilian surfer Savio Carneiro riding the Pororoca.

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Scenery - Surfing in the middle of the Amazon rain forest can be a magical experience.

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Fun - Surfers share a long Pororoca wave in the river.

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Ready to ride the beast - Brazilian surfers prepare to catch the thunderous tidal bore wave during a competition on the Mearim river.

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Daring surfer - Brazilian surfer Noelio Sobrinho rides the long Pororoca tidal wave.

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Crowd - A crowd gathers on the river bank to support the surfers who brave the Amazon's wave.

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Fun ride - Brazilian surfer Marcelo Bibita having a good time riding a long left.

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Surfing the wave - Noelio Sobrinho, another Brazilian surfer who ventures into the waters of the Mearim river.

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Local rider - Sergio Laus can be seen riding the Pororoca wave.

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Not just a surfer's wave - A Brazilian bodyboarder does a spin on a wave.

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Ready to go - Rider Noelio Sobrinho jumps into the water to catch some waves.

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Competition - Ricardo Tatui (L) and Rogerio Dantas (R) ride the Pororoca.

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Local support - The locals cheer the surfers riding the Pororoca.

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Catching the wave - Surfer Rogerio Dantas jumps into the Mearim River to catch a wave.

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Man overboard -

A man dives into the Mearim River to escape the devastating force of the Pororoca wave during a competition.

See also: Stunning pictures of the world's strangest and rarest weather phenomena

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