People are shocked at one thing after seeing video of cargo ships in rough seas

Ever seen footage of cargo ships sailing across the seven seas and simply wondered 'how do they do it'?

Chances are, you're not the only one.

In the not too distant past, videos showing ships stacked to the brim with steel containers navigating the terrifyingly unpredictable open waters went viral across social media.

Usually accompanied by a bass heavy version of the song 'Hoist the Colours', the videos show crews navigating waves twice the size of the ship and proving that a life at sea is not for the faint-hearted.

And yet these voyages are essential to maintaining global trade, as approximately 90 percent of goods are bundled into shipping containers and reach their intended destination by sea (via EMSA).

Such as the example in the video below:

The clip, which was uploaded to YouTube over a decade ago, provides us with a glimpse of what ferrying goods around the world looks like on a particularly bad day, judging by the seriously violent waves smashing into the ship.

Naturally the video left people with numerous questions, with most people wondering how the containers are even able to make it back onto dry land in one piece.

"With such a storm, the ship could arrive with half of the containers it was carrying," one person joked in the comments, while a second asked: "Always make me wonder how the containers stay in place! Anyone know?"

Why don't shipping containers fall off cargo ships?

Fortunately for anyone whose ever bought a product manufactured abroad (which is all of us here), container ships don't follow a 'load it up and hope for the best' system when it comes to transporting cargo.

Instead, there's a number of different mechanisms in place to make sure the containers all stay in place, no matter how precarious those stacks upon stacks metal boxes look.

See the holes on the sides of the containers? These are responsible for securing them together (Getty Stock Images)

At the corner of every shipping container is a hollow square block with three holes facing on all outer corners.

When shipping containers are then stacked vertically, twistlocks are used to secure each one together, minimising the risk of anything rolling off in the middle of the Atlantic Ocean.

Secure the containers together using twist locks and congratulations, instead of single containers you have stacks of containers.

However this doesn't solve the issue of attaching the containers to the ship itself, which is where metal bars are used to secure each container stack to the ship's structure.

You can see how the containers are secured to the ship with metal bars here (Getty Stock Image)

When both steps are completed the shipping containers should not only be locked together, but secured onto the ship.

After that point, if your goods get lost at sea, then it's simply a case of bad luck.