It must be beautiful, but is said to be very dangerous. It is the so-called cross sea or square waves.
There are different types of waves, especially at the most famous surfing beaches in the world . There, the waves are really round. And people travel around the world to find them.
Dangerous they are too, but apparently you can learn to ride them. But no surfer wants to meet the square waves. If you are in the water together with them, the chance of losing your life is quite high.
Waves move on the water in different directions depending on which way the wind is blowing. When the wind changes direction, the waves in the new direction can meet those in the old direction. Old waves with new waves, so to speak. This could happen if a cold weather front suddenly passes through.
And then it can happen that these waves take on a checkerboard pattern.
This happens extremely rarely. It happens when these counter-propagating waves encounter obstacles. This causes them to change direction. And this becomes dangerous even for experienced ship captains.
This wave looks quite harmless on the surface, but the square rectangular waves create extremely deadly water currents underwater. In theory, square waves have the potential to capsize large ships. Ships are designed to meet waves head-on. If the waves hit the ship from multiple angles, they will not stay afloat.
The phenomenon of rectangular waves sometimes exists near the island of Île de Ré on the west coast of France. Beautiful but scary.