What Is Thalassophobia?

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Thalassophobia is an intense fear of deep bodies of water. People with thalassophobia experience sudden onset of anxiety when exposed to triggering stimuli, which can include deep pools, the ocean, or lakes.

Everyone experiences thalassophobia differently. Some people might panic when swimming in deep water, being on a boat, or no longer being able to touch the bottom of a pool. Others experience fear just thinking about the ocean, or when looking at pictures of deep water.

Woman with goggles swimming below the surface in dark water

Marialena Chioti / EyeEm / Getty Images


Thalassophobia, often called "fear of the ocean," is a specific phobia involving intense fear of deep bodies of water. Thalassophobia is a specific phobia and is therefore classified as an anxiety disorder in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5).

People with specific phobias experience intense fear, triggered by a specific stimulus, which is disproportionate to the situation and causes significant distress or impairment.

When left untreated, thalassophobia can greatly limit a person's life. A person with thalassophobia may feel increased anxiety and quit engaging in formerly enjoyed activities such as going to the beach with friends and family, boating, swimming, watching certain movies, and more.


Thalassophobia shares symptoms with other specific phobias, such as claustrophobia. The defining characteristic of thalassophobia, compared to other specific phobias and anxiety disorders, is that these symptoms are triggered by exposure to deep bodies of water.

Symptoms of thalassophobia can include:

  • Sudden onset of anxiety or fear
  • Shaking and trembling
  • Sweating
  • Dry mouth
  • Increased heart rate or heart palpitations
  • Difficulty breathing, including hyperventilating
  • Chest pain
  • Fear of losing control or dying

Thalassophobia Triggers

Thalassophobia triggers can include:

  • Ocean
  • Pools
  • Lakes
  • Boating
  • Swimming
  • Photos of deep water
  • Not being able to touch the bottom when in water
  • Movies featuring themes of deep water, such as Jaws

Compared to many other specific phobias, thalassophobia may be dangerous. Drowning is a risk when experiencing a panic response when in deep water.

It might help to remember that the dangerous thing here is your panic response, and not the water itself. If you know you have untreated thalassophobia, it can also help to always swim with another person, or in the sight of a lifeguard.


Specific phobias, such as thalassophobia, can be diagnosed by your primary care provider, or a mental health professional such as a psychiatrist. Diagnosis typically involves a few questions about the specific fear, avoidance behaviors, persistence of the fear, and any life limitations that have resulted from the fear.

To meet the DSM-5 criteria for specific phobia, a person must demonstrate:

  • Unreasonable, excessive, or disproportionate fear of a specific stimuli; In the case of thalassophobia, this would be fear of deep water
  • Consistent and immediate anxiety response when exposed to the feared stimuli (deep water)
  • Avoidance of the feared stimuli (deep water)
  • Persistence of fear for at least six months
  • Clinically significant distress or life impairment due to anxiety and avoidance behaviors

In previous editions of the DSM, a person also had to demonstrate insight that their fear was irrational, or disproportionate to the situation.

As of 2013, a person no longer has to understand that their fear is irrational. Therefore, someone with an intense fear of deep water might think that their reaction is justified and sensible, even if it limits life activities or causes significant distress.

If you or a loved one are struggling with a phobia, contact the Substance Abuse and Mental Health Services Administration (SAMHSA) National Helpline at 1-800-662-4357 for information on support and treatment facilities in your area.

For more mental health resources, see our National Helpline Database.


The causes of specific phobias, including thalassophobia, are not totally understood, and may differ from case to case. Specific phobias, such as thalassophobia, are believed to be caused by a combination of genetic and environmental factors.


Research shows that certain genes are associated with certain specific phobias, but as of yet no studies have looked at the genetics behind thalassophobia. However, there is still believed to be a genetic factor to phobias like thalassophobia, following the Darwinian theory of evolution.

Our ancestors were afraid of deep bodies of water, and it is likely that those who were cautious of the dangers of deep water may have lived longer to pass down their genes. This theory is supported by research that indicates that specific phobias are moderately heritable, although the exact percentage can vary. For example, it has been found that for specific animal phobias, heritability is around 45%.

Traumatic Events

Thalassophobia could also be caused by traumatic events. A childhood near-drowning experience, witnessing a shark attack, never learning to swim, or even being told scary stories of the ocean are just a few examples of possible events that could trigger thalassophobia.

By associating a specific situation, such as being in deep water, with a panic response, a phobia of that situation can develop over time.


Phobias, like thalassophobia, are chronic conditions that can worsen over time and limit relationships and life activities. They are also highly treatable, although the treatment isn't always pleasant.

Unfortunately, only about 10-25% of people with a specific phobia ultimately seek treatment. This is likely due to avoidance behaviors, because treating a specific phobia does often involve confronting the feared stimuli.

Exposure Therapy

Exposure therapy is a popular and effective choice for treating specific phobias, including fear of the sea. During exposure therapy, a person is exposed to their feared stimuli in increasing levels of intensity, until fear extinction is reached.

For someone with thalassophobia, this might start with looking at photos of the sea, escalate to watching videos of the ocean or deep water, and culminate with a trip to the ocean or a pool.

Through controlled exposure, the person learns that the feared stimulus is not dangerous, and they can begin to associate it with more positive outcomes.

Both single-session and multiple-session exposure therapy can be effective at reducing symptoms of specific phobias, although a 2008 study did find that multiple sessions can be marginally more effective than a single session.

Cognitive Behavioral Therapy (CBT)

Cognitive behavioral therapy (CBT) is a type of psychotherapy that is effective at treating a variety of anxiety disorders, including specific phobias.

In CBT, a person learns insight into their own thought patterns and behavioral responses. Through this insight, they are able to alter maladaptive thoughts and subsequently change their behaviors and feelings.

For specific phobias such as thalassophobia, CBT is often used as a complementary treatment in addition to exposure therapy. However, some people might prefer CBT to exposure therapy because it requires tolerating less initial distress.


There are many reasons that people develop thalassophobia. The ocean can be a scary place, representing the unknown and the uncontrollable.

Even floating in a lake or a deep pool, not knowing what is below you, can be frightening. This is not helped by the movie industry or news media, which often share horror stories of rare shark attacks or boats sinking.

However, sometimes a reasonable fear of deep water can grow out of control. If you experience intense fear and panic around deep water, and if you avoid being around the ocean or pools as a result, then you might have thalassophobia.

Talking to your healthcare provider or a trusted friend or family member can help you cope with your phobia. Exposing yourself to water, rather than avoiding it, can also help reduce your fears, especially if done with the help of a mental health professional.

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6 Sources
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