For most people, nothing says relaxation quite like spending a day enjoying themselves out on the water. The sunshine and the open ocean are like a natural tonic.

However, for others, the ocean is the opposite of relaxing. Instead of being soothed by the sound of crashing waves, they look at the ocean and feel nothing but abject horror.

People who feel this way likely suffer from thalassophobia, which is defined as “a fear of the open ocean and what lies beneath its surface.” To find out if you have this phobia, look at the photos below!

Take a moment and look at this photograph. What do you see? Most people looking at this picture just see a baby enjoying a leisurely float inside his inner tube. However, some people see something very different…

While you might see an image like this one and think “neat!” or “how beautiful,” people with thalassophobia will interpret this sight and feel nothing but pure, unadulterated terror shake them to their very core.

So, what is thalassophobia? It is defined as being “an intense and persistent fear of the sea and sea travel.” It is characterized by waves of panic when confronted with the murky unknown depths of the ocean.

If an average person were to look at this photograph of tentacle-like seaweed being pulled by this massive wave, they would think it was awe-inspiring—but nothing frightening. A person with thalassophobia, on the other hand, would be terrified.

For some people with this phobia, everything about the ocean in general is scary. For others, their fear is more specific. It isn’t the water necessarily that they dread; it’s what is lurking beneath the water that scares them.

For some people who suffer from this phobia, their sense of panic is triggered whenever they are presented with the concept of being far away from the land. This makes water-related activities like sailing a torment instead of a soothing and relaxing adventure with their friends.

For people with thalassophobia, the ocean is not something beautiful; rather, it is something that holds all of their deepest and darkest fears. For them, even the thought of dangling their legs off a pier is too horrifying a notion to even contemplate.

It isn’t just the open ocean and its deep waters that trigger people with this phobia, either. It is also knowing that there are all sorts of strange creatures lurking just beneath the surface, sitting there, waiting…

Having this phobia doesn’t only mean that they are terrified of the ocean or the sea; it means that they may get scared when they are confronted with any large or dark body of water. They simply can’t handle the vast emptiness that it represents.

For those who harbor this terrible fear, certain images—like this one of a huge whale that’s about to surface under this small boat—aren’t a beautiful example of the natural world. Instead, they are proof that there are just too many dangers when it comes to the sea.

When you see a picture like this one, it becomes easier to understand where people with this phobia are coming from. After all, it wouldn’t take very much effort or energy at all for this whale to upend that tiny boat!

Even if you don’t have thalassophobia, it would be terrifying to be swimming around, minding your own business and enjoying the feel of the water near the pier, only to spot this shark swimming not too far off. Yikes!

If you thought the deep blue sea’s various creatures and monsters were unnerving, they’re nothing compared to the beasts that used to roam the prehistoric world’s oceans and waterways. Of course, the Jurassic period’s liopleurodon and its cousins are long extinct, but with films like Jurassic World blowing up at the box office, it’s enough to keep the fear alive!

For some people, the ocean presents itself as an exciting opportunity to explore a very special corner of the world. For people with thalassophobia, however, underwater drop-offs like this one are the embodiment of fear.

If you do not have thalassophobia, then this photograph is actually pretty calm and soothing to contemplate. But if your greatest fear is the gaping emptiness of the abyss, then this image is 100% pure nightmare fuel.

If a professional or amateur deep-sea fisherman was to discover that this glorious octopus had taken their bait, they would be ecstatic. A person with thalassophobia, on the other hand, would have one more reason to never visit the ocean again!

People with thalassophobia often also suffer from aquaphobia, which is—you guessed it—a fear of the water itself. The fact that jellyfish this humongous live in said water probably doesn’t help that fear very much…

Meanwhile, some water-lovers have a hard time even understanding how anyone could experience this kind of phobia. This gentleman is so comfortable underwater that he doesn’t think twice about grabbing this giant propeller.

Still, there are many creatures in the ocean that should inspire fear in everyone. After all, very few people want to be pursued by a shark as they kayak through the open ocean. Can you even imagine being the man in this photograph?

Thankfully, if you think that you suffer from thalassophobia, there is hope! Many sufferers of this particular phobia have found great success using cognitive behavioral therapy (or CBT) to help them learn to overcome their fears.

Thalassophobia might sound a little foolish to water babies, but when you think about it, being afraid of what you don’t know is actually kind of logical! Thank goodness there’s a treatment for it.

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