Pororoca, Brazil
The Pororoca in Brazil is a huge wave. Reaching 13-feet in height, Pororoca happens when the moon is at just the right phase. Whenever there’s a new or full moon, the ocean tide is at its highest and water flows in from the Atlantic, reversing the way which the Amazon river’s water flows. A tidal bore audible to people nearby is the result of this phenomenon. Although it’s ridiculously dangerous, it has become popular amongst surfers for that exact reason.