Daniel and Lena were hiking along a coastal cliff when Lena noticed something strange below. The ocean, usually rolling in one steady direction, had formed a pattern of intersecting lines that looked almost like a giant grid. She immediately pulled out her phone and began recording. From their high viewpoint, the square-shaped waves looked beautiful and strangely organized. Daniel had seen photographs of similar conditions before, but he knew the appearance could be misleading. Two different wave systems were crossing at an angle, creating what is known as a cross sea. Instead of moving together, the waves were meeting from different directions, making the surface increasingly complicated.

Lena wanted to get closer to the shoreline for a better video. Daniel looked toward the water and noticed that the waves were becoming steeper and more powerful. He warned her that the unusual pattern was not something to approach. As they watched, the crossing lines became sharper, and the calm appearance began to disappear. Then Daniel noticed several swimmers farther down the beach moving toward the water. He quickly turned to Lena and said they needed to warn them, because what happened next could make the beautiful pattern far more dangerous.