When natural forces are involved, people are mostly torn between fear and fascination. They are looking for the challenge to come into contact with these forces. At the same time, everyone has to respectfully recognize these elemental forces, sooner or later. This becomes impressively apparent in surfing, when a person is gliding on a metre high wave on a surf board. If he manages to stay in front of the crest, and not to be rolled over by the breaking of the wave, he is the winner and in the belief to control the element. If he is not able to do so, it mostly turns dangerous or at least uncomfortable. It is a risky game.
Usually, waves are caused by wind that blows above the water surface. The torrents of water surges are very long in the open sea and therefore rise gently, even though the size of the wave is often high. The waves turn steeper closer to shore, where they roll over the beach as surging billows.
But there is also another way in which waves are generated that can be closely linked to the moon, the so-called tidal wave. These are waves that are caused by the flood and move upstream from a river mouth. This is taking place at many rivers worldwide, the bigger the river, the higher the wave.
Let’s take the Amazon for example. In February and March, the river carries very little water. When a spring tide occurs at the full moon (opposition sun and moon) or the new moon (conjunction sun and moon), namely a large flood, tidal waves are created flowing upstream for miles, with a height of several metres. Due to the resulting noise, this phenomena is called »Pororoca« by the local Indians, meaning »loud noise«.
Surfers use this wave to ride for many minutes and sometimes for many kilometres. The high fresh water content poses a great difficulty, because it gives much less support than salt water. Also, swept along trees and bushes exacerbate surfing. Furthermore, alligators, snakes, stingrays and piranhas have been known to inhabit these waters. So it appears to be advisable to extensively practise in advance.
You can find some clips on YouTube, here an example (1:53 min):
Because the full moon or the new moon occur during the day or at night, it might be interesting to know, whether the »Pororoca« is also being surfed on at night, but we could not find any information or pictures of this. This would indeed produce quite an impressive atmosphere in the full moon light and require a high degree of courage.