What Is a Cross Sea? The Surprising Reason Waves Can Clash

Most of the time, ocean waves roll smoothly and parallel to the shoreline. But every now and then, the sea gets… confused.

A cross sea happens when two wave systems collide from different directions. It usually occurs when the wind from a new weather system cuts across the path of an older one. While the older waves keep moving in their original direction, the new wind creates waves at an oblique angle, leading to a grid-like pattern on the surface of the water.

It’s a beautiful but dangerous phenomenon—and definitely not the kind of waves you want to surf.