Rare footage shows dangerous 'square waves' that mean you should get out the sea instantly

When most people think of waves, the first thing that comes to mind is rolling, straight lines which crash into the shore and are ridden by surfers around the world.

However, the sea is notoriously unpredictable and is home to all sorts of dangerous weather phenomena lurking beneath its currents.

Not all waves move to and from the shore in straight lines, with some of the more unpredictable wave patterns being life threatening to even the most experienced swimmers.

Square waves are one of the many dangers swimmers need to be aware of, with cameraman Razvan Fiathas capturing rare footage in the ocean and uploaded it to YouTube to highlight what the dangerous phenomenon looks like in real life.

Waves are generated by the wind in the area, and when two particularly strong weather patterns collide, it can make an unusual grid-like pattern in the sea.

In the clip above, the waves can be seen crashing into each other at several different angles before as the tide comes in and out the of the shore.

Commonly known as a square waves or cross waves, these nonparallel waves form at different angles and while they are intriguing to observe from the shore, these waves can prove fatal for even the most strongest of swimmers.

The rare phenomenon of square waves were captured on camera. (YouTube/Razvan Fiat)

Square waves can form within minutes and reach up to 10 feet in height before being swallowed back into the water, something swimmers would certainly struggle to make their way out of.

The square waves are also often associated with riptides - a strong offshore current that is caused when the tide pulls water along the beach.

You should evacuate the water immediately if you see one forming.

It's not only swimmers who need to be aware of phenomenon either, with the waves also being responsible for several shipwrecks over the years, according to the European Space Agency (ESA).

People should always be cautious when swimming in the ocean, regardless of what kind of waves they encounter. (RODGER BOSCH/AFP via Getty Images)

However, outlet Surfers Hype has argued that the waves aren't always life-threatening, urging swimmers and surfers to always take appropriate care no matter what kind of water they're in.

"Always be careful in the ocean and do not surf in waves if you feel you might be out of your depth," the site advised.

The site also reassured readers that square waves are mostly a threat in the deep ocean and that opposing waves spotted nearer the shore are 'much-diminished' in power - meaning that you are less likely to be swept out to sea if you're just dipping your feet in the water.