While you may know a thing or two about traditional rip currents and changing tides, you may not be aware of the dangers of square waves. Yes, this is a real thing — and a truly stunning phenomenon at that — but it's also one of the most dangerous sights to see in the water.

Known as a "cross sea," a square wave occurs when two swells meet to form a square, often resembling a checkerboard pattern. As the European Space Agency explained in 2010, "The conditions are quite common in the ocean and occur when a windsea and a swell, or two swell systems, coexist." It pointed to a 2004 study that showed "a large percentage of ship accidents occurred in crossing sea states."

But these cross seas can form swells up to 10 feet high, as well as create unique wind patterns, making it difficult for boaters to navigate and swimmers to make their way through. So, again, while rare, if you do stumble across this, avoid heading out via a boat or swimming in the potentially rough seas.

https://www.travelandleisure.com/travel-tips/square-waves-cross-seas-danger


https://www.youtube.com/watch?v=hS3jEcCEaHw

If you see square waves in the ocean, get out of the water as soon as possible. Why? Because the phenomenon is usually associated with strong and powerful rip tides.

Swimming or surfing in the middle of a cross-sea is not something you should be doing, even if you're an experienced swimmer or wave rider.

https://www.surfertoday.com/surfing/what-are-square-waves

Thanks!