COMMISSIONS: CHASING RIVER MONSTERS / ESPN
When high tides during the spring equinox crash into slower-moving water in the Amazon River, a natural phenomenon called a tidal bore -- or a pororoca in Portuguese -- is formed. The resulting wave can rage for dozens of kilometres, ripping out trees, spewing out mud and even dragging caimans along with it. While locals live to respect the pororoca, knowing full well it could smash through their dock or turn their boat into a million wood chips, surfers live to ride it.
"It's a feeling of freedom, it's a feeling of discovery," said surfer Serginho Laus. "You are in a place that nobody goes: Everybody is afraid to go because the pororoca looks like a monster for the locals who live around this area. It's like an Amazonian tsunami."